下列哪一个不属于质谱的质量分析器？（）
A.电子倍增器
B.离子阱
C.四级杆
D.飞行时间
参考答案：A
His health ________ because his business broke up.[ ]
A. broke out
B. broke down
C. broke off
D. broke into
总大肠菌群（）
A.100个/ml
B.100个/3ml
C.3个/ml
D.每100ml水样中不得检出
E.100个/1000ml
