Mary ______ with her mother now.[ ]
A. shops
B. shopping
C. is shoping
D. is shopping
答案:C
二进制数1101001用十进制表示为______。
A.209
B.18
C.105
D.57
胸外心脏按压的正确姿势为()
A.如图A所示
B.如图B所示
C.如图C所示
D.如图D所示
E.如图E所示