_____ to too much sunlight, as is generally considered, will add to the potential of catching skin cancer.
| A．Being exposed | B．Exposed | C．Exposing | D．To expose |
________ a child begins school, he enters a world of vicious competition where success and failure are clearly defined and measured.
| A．Before | B．Until | C．Whenever | D．The moment |
Newton is known as a gifted scientist with very human weaknesses who stood at the point in history _______ magic ended and science began.
| A．that | B．when | C．where | D．which |
Researchers claim to have found the first proof _______ getting a regular eight hours a night really does make you appear healthier and more attractive.
| A．as | B．that | C．how | D．which |
Mr. Crossett was made __________ his experiment because of his poor health and old age.
| A．give up | B．giving up | C．to give up | D．given up |
It was for a lifetime of unselfish work among the sick natives ______ the old doctor deserved to be honored.
| A．who | B．that | C．which | D．whom |