单项选择题

The early achievements in space exploration were all crash-landings, each spacecraft _________.
A、 in destroy
B、 destroying
C、 being destroyed
D、 having been destroying

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不定项选择

One of the things that decides whether an applicant can be accepted by a college is his or her scores on the Scholastic Aptitude Tests.

A．错误
B．正确

单项选择题

The standard error of the mean

A．is never larger than the standard deviation of the population.
B．decreases as the sample size increases.
C．measures the variability of the mean from sample to sample.
D．All of the above.