我国规定的安全电压：交流有效值为50V，直流非脉动值为（）V。 A.48 B.80

按要求完成句子。

1.Here is a recipe for a great turkey sandwich.（改为复数形式）  

Here________ for great turkey sandwiches.

2.Put the mayonnaise on a slice of bread.（改为否定句）  

________  ________ the mayonnaise on a slice of  bread.

3.There are two glasses of orange on the table.（对画线部分提问）

  ________  ________ glasses of orange________ ________ on the table?

4.Mary wants some apples.(改为同义句）  

Mary________  ________ some apples.

5.I want to buy a bowl of rice.（对画线部分提问）

________  ________ rice do you want to buy?

Computer hardware engineers research, design, develop, and test computer hardware and supervise its manufacture and (73) . Hardware refers to computer (74) , circuit boards, computer systems, and related equipment such as keyboards, modems, and printers.

A．chips

B．frame

C．structure

D．cell

患者，男，56岁。心前区疼痛，时发时止，痛时向左臂放射。应首先考虑的是

A．胸膜炎
B．自发性气胸
C．肋间神经炎
D．带状疱疹
E．心绞痛

（）主要针对区域性生态保护和环境污染防治领域，是一项具有经济激励作用、与“污染者付费”原则并存、基于“受益者付

A.生态补偿机制

B.循环经济

C.绿色产品

D.可持续发展