A:x=1y=1
B:x=2y=0
C:x=1y=-1
D:x=-1y=-1
草履虫是单细胞生物,没有专门的运动器官,可以靠____的摆动在水中做旋转式前进,氧气的摄入和二氧化碳的排出通过____实现.
Larry, we're glad you have arrived. We ______ to drive to the station to meet you.
yōu fāng
piāo bó
wéi dú
dùn shí
____