He did very badly on the exam. He ___harder.A.must study B.must have studied C.should study D.should have studied本题答案选D,AC为什么错误呢,不能表示之后他必须或者应该好好学习吗?肯请老师解答,感谢!
...eing no taxi
available, he had to walk home. 由于没有计程车可搭,他只好步行回家。这类结构有时可与状语从句转换,如上面两句也可作如下改写:As there was nothing
to do, I went to bed. As there was no taxi
available, he had to walk home. 另外,there being...