单项选择题
A.see
B.seeing
C.be seen
D.being seen
单项选择题 In the IMO SMCP the situations（）phrases using the work “can” appear it clear whether a possibility is referred to.
单项选择题 （）it is advisable to remain on a VHF channel 8, say: “stand by on VHF channel 8”.
单项选择题 （）we stand away from the church bell, it takes time for the sound waves to each us.