油中溶解气体检测,油样在运输、保管过程中要注意样品的防尘、防震、避光和干燥等。油样的保存不得超过()。
A.1天
B.2天
C.3天
D.4天
参考答案:D
Henry broke the window .I’ll ask him why __________ .
A.did he do that
B.he did that
C.had he done that
D.he had done that
青霉素抗菌的作用机制是().
A.裂解肽聚糖的β-1,4糖苷键
B.抑制肽聚糖中四肽侧链与五肽交联桥的联接
C.破坏细菌胞膜
D.干扰细菌蛋白质合成
E.抑制细菌DNA的复制