The reason ____ the people in the mainland go to Hong Kong to buy formula is that people are not convinced ____the safety of formula produced in the mainland.
While intelligent people can often simplify the complex, a fool is more _________ to complicate the simple.
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 _________.