在以上症状中，与修复体外形有关的有（） A．疼痛 B．牙体磨损 C．修复体松动 D．

一台发电机的输出功率为50KW，所用输电导线的电阻为100Ω，当发电机的输出电压为250V时，在导线上损失的功率为______W，若改成50KV的电压输电，则导线上损失的功率为______W．

用所给单词的适当形式填空。

1. When we got there, all the beautiful birds had            (appear) in the forest.

2. You are very confident to make a____(speak) in front of the whole school.

3. Many children in Tibet can get a good____ (educate) now.

4. More and more schools will be            (build) in our hometown next year.

5. Many countries are paying more attention to the____(pollute) around us.

H2受体拮抗剂按结构类型可分为

A．咪唑类、呋喃类、噻唑类、哌啶甲苯类

B．哌嗪类、呋喃类、咪唑类、吡唑类

C．嘧啶类、咪唑类、哌啶甲苯类、呋喃类

D．噻唑类、哌啶甲苯类、咪唑类、吡唑类

E．噻吩类、吡咯类、呋喃类、哌啶甲苯类

电泳

32岁妇女，曾足月分娩1次，流产2次。产后即出现闭经。妇科检查未发现异常，该患者闭经与以下病史中，关系最密切的是

A．月经初潮16岁

B．其母38岁即闭经

C．5年前分娩，曾发生产后大出血

D．20岁时因乳腺纤维瘤作过手术

E．1年前曾先后作过两次人工流产