世界上最早的卫星导航系统是美国的子午仪导航系统。（ ）
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GPS可在24小时内任何时间进行观测，但会受到刮风、下雨、下雪等气候的影响。（ ）
A. 对
B. 错
Little _____ about him when I first met him in that company.
A. have I known
B. had I known
C. do I know
D. did I know
At no time, and under no circumstances _____ the first to use nuclear weapon.
A. China will be
B. will be China
C. will China be
D. shall China be
Only when you have acquired a good knowledge of grammar _____ fluently.
A. you will write
B. can you write
C. you can write
D. you could write
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