患者王先生，在工作时不慎被生锈铁钉刺破右脚，伤口较深，需注射破伤风抗毒素，皮试为阳性

三棱锥V-ABC中，VO⊥平面ABC，O∈CD，VA=VB，AD=BD．证明：CD⊥AB且AC=BC．

我国的根本政治制度是（     ）

A．社会主义制度

B．政治协商制度

C．人民代表大会制度

D．民族区域自制制度

用括号内词的比较级填空。

1. Tom thinks he works hard. But in fact Jacky works even _____. (hard)

2. Tom is as _____ (clever) as Jacky. But he isn't as _____ (hard-working) as

Jacky.

3. Jacky's Chinese is the _____ (good) in his class. But Tom thinks Chinese is the_____ (difficult) of all.

4. Tom spends _____ (few) toys than tom, but he has _____ (many )books.

烤瓷熔附金属全冠适用于（）

A．锥形牙

B．横行冠折，达牙槽骨以下

C．切角小范围缺损

D．横行冠折，达牙槽骨以上

E．近中邻面龋

胚胎在器官发育期受到有害因素作用可引起

A．月经失调
B．自然流产
C．胎儿畸形
D．遗传病
E．低出生体重儿