It is hard for us to eat better, exercise more, and sleep enough, ________ we know we should.
I was about to go to bed _____ one of my old classmates made a call to me.
Only those ____knew well could be let in.
The criminal, as well as some ______ people, was arrested by the police yesterday.
____ with the size of the whole earth, the highest mountain doesn’t seem high at all.
I ______ my university professor in the supermarket near my house, which was out of my expectation.