ground be covered with acorns

例句：

1. 1.The ground is covered with acorns.
   地面被橡实覆盖。
2. 2. The ground was frozen solid during the winter.
   冬天，地面冻得硬邦邦的。
3. 3.The ground shook as an earthquake struck.
   地震发生时，地面震动起来。