—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
___ more and more people may refer to the Internet for the latest news, it is unlikely that the newspaper will disappear.
—I'm sorry; I shouldn't have been so rude to you.—You ___ something not very nice to me, but that's OK.
—Can you describe ___ it happened?—Yes, I was riding on my bike ___ a car knocked me down from behind.
The train CRH380A, ___ trial operation on the Shanghai-Hangzhou high-speed railway, set a speed record of 416.6 kilometers per hour.
We went to the West Lake yesterday, ___, not surprisingly, was crowded with visitors from all over the world.