导致化脓性感染的致病菌中，"大量存在于肠道内，其单独致病力并不大。单一感染产生的脓液

1990年3月，哪个国家的独立标志着欧洲殖民者入侵和奴役非洲长达五个世纪历史的结束？[ ]

A．埃及

B．纳米比亚

C．古巴

D．巴拿马

人耳能分清前后两个声音的时间间隔应大于0.1s，据此，要想听到回声，人离障碍物的距离应　　　　　　　　　　　　　　　　　　　　　　　　　　　         （    ）

A．大于17m

B．小于17m

C．大于34m

D．小于34m

Zhang:  Hi, Amy. How are you?

Amy:   Hi, Zhang. I'm glad to see you.

Zhang:  Me too. My friend Mary said you had 小题1:___________ ill for a few days. Are you OK?

Amy:    I am feeling well now. Thanks. But today I was very upset.

Zhang: Why? What小题2:___________ to you?

Amy:    First of all, my alarm clock didn’t go off this morning. So I was late at the bus stop. The bus had already left 小题3:____________ I got there. Then I had to walk to school.

Zhang: That's a long walk.

Amy:    Yeah. And then it started 小题4:__          and I'd forgotten my umbrella.

Zhang: Oh no! Did you get wet?

Amy:    Yes, I was late and wet. You know we will have a physics test tomorrow but I missed the class.

Zhang: I am sorry to hear that. You did have a bad day. But I am sure you will get good

小题5:___________ in the physics test. You are always good at it.

Amy:    Thanks. I will try my best.

按规范确定钢筋混凝土构件中纵向受拉钢筋最小锚固长度时，有下列因素：Ⅰ．混凝土的强度等级；Ⅱ．钢筋的钢号；Ⅲ．钢筋的外形(光面、带肋等)；Ⅳ．钢筋末端是否有弯钩；Ⅴ．是否有抗震要求。上述哪些因素是应考虑的

A．Ⅰ、Ⅱ、Ⅲ、Ⅳ
B．Ⅰ、Ⅱ、Ⅲ、Ⅴ
C．Ⅰ、Ⅲ、Ⅳ、Ⅴ
D．Ⅱ、Ⅲ、Ⅳ、Ⅴ

机转子在运行中均会受到（），这种力的平衡主要是由平衡盘和推力轴来克服。