—Excuse me, Maria. Can I use your bike?—Sure. Here you are. But you must return it _____ time.
A:in
B:at
C:on
D:to
设U为全集,对集合X,Y,定义运算“⊕”,满足X⊕Y=CUX∪Y,,则对于任意集合X,Y,Z,则X⊕Y⊕Z=( )
⑴____ A.photo B. box C. clock D. lost
⑵____ A. thank B. think C. thing D. brother
⑶____ A. brown B. know C. now D. how
⑷____ A. food B. good C. school D. room
⑸____ A. blue B. bus C. lunch D. number