车轮外倾和（）共同作用互相抵消轮胎的滑拖现象，减小轮胎的磨损。 A.主销内倾 B.主

用所给动词的适当形式填空。

1. Tony often ______ (go) online at weekends.

2. ______ his brother often ______ (play) computer games?

3. Mary and her sister ______ (send) emails on the computer but they ______ ______ ( not play )

    games on it.

4. First, use the mouse ______ ______ (click) "new document".

5. His father ______ ______ (not watch) TV every evening but he often ______ (write) novels on his

    computer.

关于胎盘的功能下列哪些是正确的()

A．保护母体功能

B．保护胎儿功能

C．合成功能

D．营养物质供应

E．气体交换

改良Heller术的手术要点不包括（）

A.切断食管下段一侧所有环行肌纤维

B.贲门部食管肌层切开长度不超过2cm

C.食管下段肌层切开长度至少应达8～10cm

D.常规做胃底折叠术以防胃一食管反流

E.术中应注意勿损伤胃一食管返折

绩效衡量基线为（）。

A、计划价值

B、挣值

C、实际成本

D、计划完成工作的实际成本

苛刻条件下使用的爆破片装置应（）年更换一次。