一定量的氧气中含有1 mol电子,这些O2的物质的量为
A.1 mol
B.0.5 mol
C.0.125 mol
D.0.0625 mol
答案:D
After long and hard struggle, his small family business began to _____. Hopefully, it will change into a large firm in the near future.
A.take over
B.take in
C.take off
D.take down
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