使用恢复期血清可提供哪一类免疫（）
A.自然主动免疫
B.自然被动免疫
C.人工主动免疫
D.人工被动免疫
E.非特异性抵抗力
参考答案：D
That party has been in ________ for many years and it has showed its ________ in dealing with
many important problems. [ ]
A. power; energy
B. power; strengths
C. force; energy
D. force; strengths
如果在晴天朗日的天气条件下曝光值为f／11x1／250秒，则在多云天气里，曝光值应为（）
A.f／5.6x1／125
B.f／5.6x1／250
C.f／8x1／250
D.f／8x1／125
