<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
<!-- 이미지란  -->
    <RelativeLayout
        android:id="@+id/relativeLayout0"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >
            <ImageView
        android:id="@+id/imageView1"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scaleType="fitXY"
        android:src="@drawable/background" />
    </RelativeLayout>
   
            <!--  이미지란의 끝  -->
            <!--  첫 번째 버튼 행 -->
        <RelativeLayout
            android:id="@+id/relativeLayout1"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:padding="10dp" >
                <ImageButton
                    android:id="@+id/a"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginRight="10dp"
                    android:src="@drawable/ic_launcher" />

                <ImageButton
                    android:id="@+id/b"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/ic_launcher"
                     android:layout_marginRight="10dp"
                    android:layout_toRightOf="@+id/a" />

                <ImageButton
                    android:id="@+id/c"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/ic_launcher"
                     android:layout_marginRight="10dp"
                     android:layout_toRightOf="@+id/b"  />

                <ImageButton
                    android:id="@+id/d"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/ic_launcher"
                     android:layout_marginRight="10dp"
                     android:layout_toRightOf="@+id/c"  />
            </RelativeLayout>
        </RelativeLayout>
        <!--  첫번째 버튼의 끝  -->
        
        
       
      소스 입니다.

이미지 처럼 d < 마지막 버튼 부분이 저렇게 벌어지는데 왜그런가요..?

딱딱 일정한 간격을 두고 싶은데 잘 안되네요...