A first magnitude star is().
A. 2.5 times as bright as a second magnitude star
B. 3 times as bright as a second magnitude star
C. 5 times as bright as a second magnitude star
D. 10 times as bright as a second magnitude star
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陆游的《剑门道中遇微雨》根据诗句中的描述当时经过剑门山时搭乘的是什么交通工具?
单班入井的最大人数大矿不得超过()人。
A. 800
B. 900
C. 1000