终聚真空系统停电恢复后，真空喷射泵应该（）。A、按顺序启动 B_爱下问搜题

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问题单项选择题

终聚真空系统停电恢复后，真空喷射泵应该（）。

A、按顺序启动

B、立即启动

C、只启动喷淋

D、只启动液环泵

答案

参考答案：A

问答题

已知元素M是组成物质NH₄Al（SO₄）₂的一种元素．元素M的气态原子逐个失去第1个至第4个电子所需能量（即电离能，用符号I₁至I₄表示）如表所示：

	I₁	I₂	I₃	I₄
电离能（kJ/mol）	578	1817	2745	11578

元素M的名称是______．

完形填空

One day Mozart saw an old blind street-performer playing the violin in the street corner 26 a hat in front of him . He found out the old man was 27 one of his compositions . The old man played for 28 but still nobody put any money into his hat . Mozart asked the old man , “Do you often play compositions by Mozart ?” “Yes, 29 _ ,” answered the old man . “now, everybody knows Mozart and likes his music .” “Do you 30 a living by playing the violin ?” The old man said he 31 . Mozart took over the violin from the old man and began to play .
He played so well 32 all the passerby stopped to listen to the wonderful music and soon the old man felt very 33 that the man could play so well . He asked Mozart , “Who are you , sir ?” “Your colleague（同行） , a poor 34 like you .”
Then Mozart gave the 35 back to the old man and went away .

C．disappointed