People have come to understand _____ prevents so many Americans from being as happy as one might expect.
| A．that it is why | B．what does it that | C．why it does that | D．what it is that |
And you find that you're not to be _____ with a position of real responsibility.
| A．offered | B．trusted | C．furnished | D．retained |
They decided to leave the waiter a big _____ because the food and service had been excellent.
| A．note | B．reward | C．tip | D．gift |
The patients believe that the doctor knows exactly how to put them _____.
| A．correct | B．perfect | C．right | D．well |
Stressful environments lead to unhealthy behaviors such as poor eating habits, which _____ increase the risk of heart disease.
| A．in turn | B．in return | C．by chance | D．by turns |
Circus tigers, although they have been tamed, can _____ attack their trainer.
| A．unexpectedly | B．deliberately | C．reluctantly | D．subsequently |