1 . 我不能和你外出是因为我必须照顾我生病的爷爷。
________________ I have to care for my sick grandfather.

2 . 他继续这个实验的原因，是因为他希望能成功的完成这项任务。(定语从句)
The reason ___________ was that he was in the hope of completing this task successfully.

3 . 句型公式: The reason why +定语从句 + is / was that + 表语从句
The biggest reason ______________ he loves China, however, ______________ he enjoys being with Chinese people.   
然而，他喜欢中国的最大原因是他喜欢与中国人待在一起。（根据汉语提示完成句子）

6 . 青少年轻微超重是正常的，没有理由为此焦虑。然而，如果超重到达到危险程度，新尝试以适当方式减重很重要。
It is normal for teenagers to be slightly overweight and there is no reason ________ they should be worried. However, for those ________ are dangerously overweight, it is very important that they try to lose weight properly.

7 . ________ his bike was broken.
他迟到的原因是他的自行车坏了。

8 . 你陷入恐慌的原因是你还没有为可能发生的是做好准备。(复合句)
The reason ________ you got into panic(恐慌)was ________ would happen.

9 . 他被惩罚的原因是他总是上课讲话。（reason后接定语从句）
The reason ________ was ________.

10 . The moment you think about giving up, think of ________.   
你想放弃的时候，想想你坚持这么长时间的原因。