7. —I called your office at about ten this morning, but there was no reply.—Oh, that was probably ________ I was paying a visit to a friend in hospital.

一个概念的内涵越多，它的外延就越少，而概念的内涵越少，它的外延就越大。（ ）

48. Why are test screenings necessary?

10. “The thirst for knowledge is the strongest ________ there is a barrier,” says the president of the Italian Union of the Blind.

校园暴力是指在校学生之间存在的言语羞辱、敲诈勒索甚至殴打的暴力欺凌行为。这类行为主要侵害了学生的（ ）。

39.

44. What advice does Herbst most likely give to teens by her camp experience?

26. She is overweight, but she can’t ________ the temptation to eat more delicious food.

3. Though we are surrounded with modern technologies, we ________ easily feel lonely.

（ ）也叫“助长性迁移”，是指一种学习对另一种学习的促进作用。

32.

53. Why do scientists clone monkeys?