数字信号（）在电缆中长距离传输。A.适合 B.不适合 C.不太适合 D.不能

（）采用上下共轴反转的两组旋翼用来平衡旋翼反扭矩。

香港特别行政区的主要旅游景点有( )。

A．太平山

B．星光大道

C．东望洋山

D．日月潭

E．浅水湾

引起组胺中毒的鱼类为( )。

A．河豚鱼
B．青皮红肉鱼
C．红肉鱼
D．内陆湖泊鱼

Her sister（）a rich man. They（）for twenty years.

A. married with; have married

B. married to; have married

C. married; have been married

D. had married; have been married

德国学者（）提出了著名的孤立国农业圈层理论即农业区位论。

A.杜能

B.韦伯

C.胡佛

D.廖什