It's not necessary to explain the truth________there are air,water and sunlight,there are living things.
When I _________ the past and think how much time has been wasted, my heart bleeds.
It was not until his father came back from work _________ the boy began to do his homework.
—When shall we meet again?—Any time that _________ you best.
—Can Bob help me with this problem?—I’m afraid it's beyond his _________.
I don't like noisy jazz. _________,I enjoy light music, which sounds soft and gentle.