安卓开发You must supply a layout_width attribute. Couldn't resolve resource @string/text1

我写的程序：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/screen"
android:layout_width="fill_content"
android:layout_height="fill_parent"
android:orientation = "vertical">
<TextView android:id="@+id/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="24sp"
android:text="@string/text1"/>
<Button android:id="@+id/button1"
android:layout_width="80sp"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="24sp"
android:text="@string/red"/>
<TextView android:id="@+id/button2"
android:layout_width="80sp"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="24sp"
android:text="@string/green"/>
</LinearLayout>
出的错：
You must supply a layout_width attribute.
Couldn't resolve resource @string/text1
Couldn't resolve resource @string/red
Couldn't resolve resource @string/green
请高手帮忙解决哦！！！

你好！

你太牛了，请问你想用这个才程序实现什么功能呢

希望对你有所帮助，望采纳。

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