叶酸是体内重要的维生紊，孕妇体内水平过低最严重的潜在危害是A_爱下问搜题

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问题单项选择题

叶酸是体内重要的维生紊，孕妇体内水平过低最严重的潜在危害是

A．妊娠高血压综合征
B．孕期严重缺钙
C．生出低体重儿
D．胎儿神经管畸形
E．伴有严重锌缺乏

答案

参考答案：D

填空题

用方框中所给单词的适当形式填空，使短文通顺、正确、连贯（每个单词限用一次）。

decide as return poor volunteer experience village meter because influence

    During the school vacation, I didn't go home. The teachers encouraged us to be 1            for
the other people. I went to a 2            mountain 3             in Sichuan Province which was 2000
4             above the sea level. (It was small and the children in the village had to stay at home to
work with their parents 5            they didn't have teachers.) I worked 6            a volunteer teacher
to junior school students. It was a new and interesting 7            for me. I was very happy I could
be a good 8            in the children's lives. I made the correct 9            to spend the school vacation
there. I enjoyed my time there and I would like to 10            some day.

问答题简答题

液压伺服系统动态特性中的“过渡过程”品质主要有那几个指标来表示？