Cook was a strict but good captain, ----,who,usually,took ca

这是一道典型考题,正确答案为A.解析如下：
整个句子的意思是：库克是一位严格但善良的船长,他经常在船上照顾水手.
代词one作为同位语,指代库克这位船长；who用于引导非限制性定语从句修饰one,进一步对库克船长如何善良进行解释说明.句中的逗号用于强调“usually”,表明照顾水手是一种经常性的事情.
句子可以改写为：Cook was a strict but good captain,and he usually took care of the sailors on his ship.进一步简化可为：Cook was a captain,and he took care of the sailors.
链接是本题的出处和参考答案（第29题）,以供参考.
再问： 再问一下这个句子化简成最简形式以后是什么呢
再答： 改写及简化形式如上所答。