无符号二进制数 11001000 所表示的十进制数为(21) 。
A.104
B.148
C. 172
D.200
参考答案:D
胚胎在母体子宫内发育成熟的时间大约是多少天( )
A.250天
B.260天
C.280天
D.300天
When he realized the police had spotted him,the man__the exit as quickly as possible.
A.made off
B.made for
C.made out
D.made up