根据首字母完成下列句子。

1. At last I r         I had left my book in the library.

2. My sister has a dentist's a          this Saturday.

3. There used to be various of animals on this t          island.

4. Our main p        is to inquire the possibility of establishing a long-term business relations with your

company.

5. But the t         is that most of the doctors are facing the moral dilemma.

安全工作规程规定，对地电压高于（）V为高压；（）V以下为低压。