该参数枚举值，采用位运算，那么可以用Or把两者连接起来即可；
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New Font(CurrentFont.FontFamily, CurrentFont.Size, FontStyle.Bold Or FontStyle.Italic)
你说的是控件中的字对齐吗？
字对齐是改变控件的TextAlign属性，该属性一共有9个属性值，
TopLeft，TopCenter，TopRight，MiddleLeft，MiddleCenter，MiddleRight，BottomLeft，BottomCente，BottomRight，分别对应：上左；上中；上右；中左；正中；中右；下左；下中；下右；
如果你说的是控件对齐窗体的话，那么直接修改控件的Location属性就可以了。比如一个按钮控件实例btn需要位于窗体正中，那么，代码应该写成：
Dim x, y As Integer
x = (Me.Width - btn.Width) / 2
y = (Me.Height - btn.Height) / 2
btn.Location = New System.Drawing.Point(x, y)
'新建一个VB.NET 项目，把原来所有代码删了，把下面的代码复制贴上去解OK了
Public Class Form1
Inherits System.Windows.Forms.Form
#Region " Windows 窗体设计器生成的代码 "
Public Sub New()
MyBase.New()
'该调用是 Windows 窗体设计器所必需的。
InitializeComponent()
'在 InitializeComponent() 调用之后添加任何初始化
End Sub
'窗体重写 dispose 以清理组件列表。
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
'Windows 窗体设计器所必需的
Private components As System.ComponentModel.IContainer
'注意: 以下过程是 Windows 窗体设计器所必需的
'可以使用 Windows 窗体设计器修改此过程。
'不要使用代码编辑器修改它。
Friend WithEvents RadioButton1 As System.Windows.Forms.RadioButton
Friend WithEvents RadioButton2 As System.Windows.Forms.RadioButton
Friend WithEvents GroupBox1 As System.Windows.Forms.GroupBox
Friend WithEvents GroupBox2 As System.Windows.Forms.GroupBox
Friend WithEvents RadioButton3 As System.Windows.Forms.RadioButton
Friend WithEvents RadioButton4 As System.Windows.Forms.RadioButton
Friend WithEvents CheckBox1 As System.Windows.Forms.CheckBox
Friend WithEvents CheckBox2 As System.Windows.Forms.CheckBox
Friend WithEvents CheckBox3 As System.Windows.Forms.CheckBox
Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
Friend WithEvents Button1 As System.Windows.Forms.Button
System.Diagnostics.DebuggerStepThrough() Private Sub InitializeComponent()
Me.RadioButton1 = New System.Windows.Forms.RadioButton
Me.RadioButton2 = New System.Windows.Forms.RadioButton
Me.GroupBox1 = New System.Windows.Forms.GroupBox
Me.GroupBox2 = New System.Windows.Forms.GroupBox
Me.RadioButton3 = New System.Windows.Forms.RadioButton
Me.RadioButton4 = New System.Windows.Forms.RadioButton
Me.CheckBox1 = New System.Windows.Forms.CheckBox
Me.CheckBox2 = New System.Windows.Forms.CheckBox
Me.CheckBox3 = New System.Windows.Forms.CheckBox
Me.TextBox1 = New System.Windows.Forms.TextBox
Me.Button1 = New System.Windows.Forms.Button
Me.GroupBox1.SuspendLayout()
Me.GroupBox2.SuspendLayout()
Me.SuspendLayout()
'
'RadioButton1
'
Me.RadioButton1.Location = New System.Drawing.Point(16, 24)
Me.RadioButton1.Name = "RadioButton1"
Me.RadioButton1.Size = New System.Drawing.Size(56, 24)
Me.RadioButton1.TabIndex = 1
Me.RadioButton1.Text = "红色"
'
'RadioButton2
'
Me.RadioButton2.Location = New System.Drawing.Point(72, 24)
Me.RadioButton2.Name = "RadioButton2"
Me.RadioButton2.Size = New System.Drawing.Size(48, 24)
Me.RadioButton2.TabIndex = 2
Me.RadioButton2.Text = "蓝色"
'
'GroupBox1
'
Me.GroupBox1.Controls.Add(Me.RadioButton2)
Me.GroupBox1.Controls.Add(Me.RadioButton1)
Me.GroupBox1.Location = New System.Drawing.Point(16, 144)
Me.GroupBox1.Name = "GroupBox1"
Me.GroupBox1.Size = New System.Drawing.Size(128, 56)
Me.GroupBox1.TabIndex = 5
Me.GroupBox1.TabStop = False
Me.GroupBox1.Text = "颜色"
'
'GroupBox2
'
Me.GroupBox2.Controls.Add(Me.RadioButton3)
Me.GroupBox2.Controls.Add(Me.RadioButton4)
Me.GroupBox2.Location = New System.Drawing.Point(176, 144)
Me.GroupBox2.Name = "GroupBox2"
Me.GroupBox2.Size = New System.Drawing.Size(136, 56)
Me.GroupBox2.TabIndex = 6
Me.GroupBox2.TabStop = False
Me.GroupBox2.Text = "字号"
'
'RadioButton3
'
Me.RadioButton3.Location = New System.Drawing.Point(16, 24)
Me.RadioButton3.Name = "RadioButton3"
Me.RadioButton3.Size = New System.Drawing.Size(56, 24)
Me.RadioButton3.TabIndex = 2
Me.RadioButton3.Text = "30号"
'
'RadioButton4
'
Me.RadioButton4.Location = New System.Drawing.Point(72, 24)
Me.RadioButton4.Name = "RadioButton4"
Me.RadioButton4.Size = New System.Drawing.Size(48, 24)
Me.RadioButton4.TabIndex = 1
Me.RadioButton4.Text = "40号"
'
'CheckBox1
'
Me.CheckBox1.Location = New System.Drawing.Point(32, 208)
Me.CheckBox1.Name = "CheckBox1"
Me.CheckBox1.Size = New System.Drawing.Size(80, 32)
Me.CheckBox1.TabIndex = 7
Me.CheckBox1.Text = "加粗"
'
'CheckBox2
'
Me.CheckBox2.Location = New System.Drawing.Point(120, 208)
Me.CheckBox2.Name = "CheckBox2"
Me.CheckBox2.Size = New System.Drawing.Size(80, 32)
Me.CheckBox2.TabIndex = 8
Me.CheckBox2.Text = "斜体"
'
'CheckBox3
'
Me.CheckBox3.Location = New System.Drawing.Point(200, 208)
Me.CheckBox3.Name = "CheckBox3"
Me.CheckBox3.Size = New System.Drawing.Size(80, 32)
Me.CheckBox3.TabIndex = 9
Me.CheckBox3.Text = "下划线"
'
'TextBox1
'
Me.TextBox1.Font = New System.Drawing.Font("宋体", 9.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(134, Byte))
Me.TextBox1.Location = New System.Drawing.Point(8, 16)
Me.TextBox1.Multiline = True
Me.TextBox1.Name = "TextBox1"
Me.TextBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical
Me.TextBox1.Size = New System.Drawing.Size(320, 112)
Me.TextBox1.TabIndex = 0
Me.TextBox1.Text = "话说天下大势，分久必合，合久必分。"
'
'Button1
'
Me.Button1.Location = New System.Drawing.Point(88, 256)
Me.Button1.Name = "Button1"
Me.Button1.Size = New System.Drawing.Size(152, 32)
Me.Button1.TabIndex = 10
Me.Button1.Text = "确定"
'
'Form1
'
Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
Me.ClientSize = New System.Drawing.Size(336, 310)
Me.Controls.Add(Me.Button1)
Me.Controls.Add(Me.CheckBox3)
Me.Controls.Add(Me.CheckBox2)
Me.Controls.Add(Me.CheckBox1)
Me.Controls.Add(Me.GroupBox2)
Me.Controls.Add(Me.GroupBox1)
Me.Controls.Add(Me.TextBox1)
Me.Name = "Form1"
Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
Me.Text = "Form1"
Me.GroupBox1.ResumeLayout(False)
Me.GroupBox2.ResumeLayout(False)
Me.ResumeLayout(False)
End Sub
#End Region
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If Me.RadioButton1.Checked = True Then Me.TextBox1.ForeColor = System.Drawing.Color.Red
If Me.RadioButton2.Checked = True Then Me.TextBox1.ForeColor = System.Drawing.Color.Blue
If Me.RadioButton3.Checked = True Then Me.TextBox1.Font = New Font("宋体", 30)
If Me.RadioButton4.Checked = True Then Me.TextBox1.Font = New Font("宋体", 40)
Dim style As FontStyle = FontStyle.Regular
If Me.CheckBox1.Checked = True Then style = style Or FontStyle.Bold
If Me.CheckBox2.Checked = True Then style = style Or FontStyle.Italic
' If Me.CheckBox1.Checked = True And Me.CheckBox2.Checked = True Then TextBox1.Font = New Font(TextBox1.Font, FontStyle.Bold Or FontStyle.Italic)
If Me.CheckBox3.Checked = True Then style = style Or FontStyle.Underline
Me.TextBox1.Font = New Font(TextBox1.Font, style)
End Sub
End Class
给点提示吧，已粗体为例（完全是我自己的方法，不知别人是怎么做的）：
'先获取选择的字体信息（字体、大小、样式。。。）
Dim currentFont As System.Drawing.Font = RichTextBox1.SelectionFont
'在重新定义某种样式的时候，不丢失其他信息
RichTextBox1.SelectionFont = New Font(currentFont.FontFamily, currentFont.Size, FontStyle.Bold)