公钥密码体制的出现,解决了对称密码体制很难解决的一些问题,主要体现一下三个方面:()、()和()。
参考答案:密钥分发问题;密钥管理问题;数字签名问题
根据所给情景,选择最佳答案。
1. 当你想问别人会不会打扑克时,应说:[ ]
A. Do you like cards?
B. Can you play cards?
C. Do you play cards?
D. Do you like to play cards?
2. 当你想问农场里有什么动物时,应说:[ ]
A. What animals are on the farm?
B. How many animals are on the farm?
C. Do you have many animals on the farm?
D. Where are the animals on the farm?
3. 当你想问别人在哪儿工作时,应说:[ ]
A. Where are you?
B. What do you do?
C. Where are you work?
D. Where do you work?
4. 当你想去动物园,需要问路时,应说:[ ]
A. Thank you.
B. I'm sorry. Where is the zoo?
C. Excuse me! Where is the zoo?
D. Where is the zoo?
5. 当你想问别人发生了什么事时,应说:[ ]
A. What is it?
B. What happened?
C. Where is it?
D. What is happen?
离心泵运转时,流量为零时,泵的功率()。
A.最大
B.为零
C.为某一数值
D.最小