搜题请搜索小程序“爱下问搜题”
问题 选择题

关于分力和合力的关系，下列说法中正确的是（　　）

A．分力和合力同时作用在物体上

B．合力的作用效果与分力共同作用的效果一定相同

C．两个分力的合力一定大于任一分力

D．合力一定小于其中一个分力

答案

A、合力与分力是等效替代关系，不是重复受力，故A错误；

B、当一个物体受到几个力的共同作用时，我们常常可以求出这样一个力，这个力产生的效果和原来几个力的共同作用产生的效果相同，这个力就叫做那几个力的合力，原来的几个力就叫做这个力的分力，故B正确；

C、D、两个分力F1、F2与合力F合的大小关系与两个分力方向间的夹角θ有关．当θ=0，则F合=F1+F2（F合最大）；当θ=180°，则F合=|F1-F2|（F合最小）．所以两个力的合力可以大于任一分力，也可以小于任一分力，还可以等于某一分力，并且在两力同向时合力最大，反向时合力最小，故C错误，D也错误；

故选B．

单项选择题 B型题

易与妊娠相混同的子宫肌瘤（）

A.玻璃样变

B.脂肪样变

C.囊性变

D.红色变

E.肉瘤样变
查看答案
单项选择题

When anyone opens a current account at a bank, he is lending the bank money. He may (1) the repayment of the money at any time, either (2) cash or by drawing a check in favor of another person. (3) , the banker-customer relationship is that of debtor and creditor who is (4) depending on whether the customer’s account is (5) credit or is overdrawn. But, in (6) to that basically simple concept, the bank and its customer (7) a large number of obligations to one another. Many of these obligations can give (8) to problems and complications but a bank customer, unlike, say, a buyer of goods, cannot complain that the law is (9) against him.

The bank must (10) its customer’s instructions, and not those of anyone else. (11) , for example, a customer opens an account, he instructs the bank to debit his account only in (12) of checks drawn by himself. He gives the bank (13) of his signature, and there is a very firm rule that the bank has no right or (14) to pay out a customer’s money (15) a check on which its customer’s signature has been (16) It makes no difference that the forgery may have been a very (17) one: the bank must recognize its customer’s signature. For this reason there is no (18) to the customer in the practice, (19) by banks, of printing the customer’s name on his checks. If this (20) Forgery, it is the bank that will lose, not the customer. (254 words)

19（）

A.engaged

B.intended

C.adapted

D.adopted
查看答案