例句與造句

1. The simple crater has a bowl shape . the complex crater has a small hill at the center , which was caused by the rebound of the material at the center
   簡(jiǎn)單環(huán)形山形狀好像一個(gè)碗，復(fù)雜環(huán)形山則有一個(gè)小山丘在隕坑中間，這個(gè)小山丘是由撞擊后物質(zhì)反彈所形成。
2. It's difficult to find complex crater in a sentence. 用complex crater造句挺難的