根据句意和首字母填写单词。

1. Students often make spelling m_____ in their compositions.

2. Can you say a c_____ sentence?

3. The teacher is very p_____ to the students.

4. The boy r_____ to answer the question.

5. Tina is a(n) h_____ child. Trust her.

甲醛、乙醛、丙酮三种化合物可用（）一步区分开。

A、NaHSO试剂；

B、席夫试剂（Schiff′s）；

C、托伦试剂（Tollen）；

D、费林试剂（Fehing）。