1 . 选择恰当的短语并用其正确的形式补全句子。

be unaware of        be known as       cheer up       look through       have yet to

1. Some specific problems ______ be solved.
2. I have ______ all my papers but I still can’t find my notes.
3. Many teenagers ______ the harm of smoking and even get addicted to it.
4. Professor Ye Jiaying ______ an outstanding researcher of classical Chinese poetry.
5. When I’m feeling sad, my mother tells me funny stories to ______ me ______.