单项选择题
A baby might show fear of an unfamiliar adult,（）he is likely to smile and reach out to another infant.
A.if B.wherever C.so that D.whereas
单项选择题 （）with the size of the whole earth, the highest mountains do not seem high at all.
单项选择题 It is useful to science（）the earth as an object in space.
单项选择题 We must（）that the experiment is controlled as rigidly as possible.
