[单项选择]What have given mankind a new viewpoint on the earth and its neighbors in space A. Those explorations. B. The advance of new technologies. C. Spacecraft studies. D. Scientific discoveries.
A. convince B. confirm C. convert D. control 参考答案:A 答案解析:题意是:他们没能______领导者其计划行得通,所以他们所有的工作都不过是浪费时间和精力。[A]convince“使确信,说服”,convince sb that...“使某人确信…”,符合题意。[B