在气体的流动过程中流体流动类型为湍流时Re（）。

A:Re＜2320 B:＞10000 C:2320＜Re＜10000 D:Re与液体流动无关

雷诺数Re可用来判别流体的流动状态，当（）时是层流状态。

A:Re小于2300 B:Re大于2300 C:Re大于1000 D:Re小于1000

雷诺系数Re可用来判别流体的流动状态，当（）是层流状态。

A:Re＜2000 B:Re＞2000 C:Re＞1000 D:Re＜1000

流体在直管内流动时，当雷诺数Re（）时，流体的流动属于湍流。

A:Re≥4000 B:Re≤2000 C:Re≥3000 D:2000≤Re≤4000

有压圆管恒定流，若断面1的直径是其下游断面2的直径的二倍，则断面1的雷诺数Re1与断面2的雷诺数Re2的关系是：（）

A:Re1=Re2 B:Re1=0.5Re2 C:Re1=1.5Re2 D:Re1=2Re2

Passage Four
Why is there no risk to the customer when a bank prints the customer’s name to his cheques
When anyone opens a current account at a bank, he is lending the bank money, repayment of which he may demand at any time, either in cash or by drawing a check in favor of another person. Primarily, the bank-customer relationship is that of debtor and creditor who is which depending on whether the customer’s account is in credit or overdrawn. But, in addition to that basically simple concept, the bank and its customer owe a large number of obligations to one another. Many of these obligations can give rise to problems and complications but a bank customer, unlike, say, a buyer of goods, cannot complain that the law is loaded against him.
The bank must obey its customer’s instructions, and not those of anyone else. When, for example, a customer first opens an account, he instructs the bank to debit (把……记入借方) his account only in respect of checks drawn by himself. He gives the bank specimens of his signature, and there is a very firm rule that the bank has no right or authority to pay out a customer’s money on a check on which its customer’s signature has been forged. It makes no difference that the forgery may have been a very skillful one: the bank must recognize its customer’s signature. For this reason there is no risk to the customer in the practice, adopted day banks, of printing the customer’s name on his checks, ff this facilitates forgery, it is the bank which will lose, not the customer.

A:must always be in credit B:can't draw any money if you're overdrawn C:can draw money without notice D:can't pay money to anyone else

Why is there no risk to the customer when a hank prints the customer’s name to his cheques
When anyone opens a current account at a bank, he is lending the bank money, repayment of which he may demand at any time, either in cash or by drawing a check in favor of another person. Primarily, the bank-customer relationship is that of debtor and creditor who is which depending on whether the customer’s account is in credit or overdrawn. But, in addition to that basically simple concept, the bank and its customer owe a large number of obligations to one another. Many of these obligations can give rise to problems and complications but a bank customer, unlike, say, a buyer of goods, cannot complain that the law is loaded against him.
The bank must obey its customer’s instructions, and not those of anyone else. When, for example, a customer first opens an account, he instructs the bank to debit (把……记入借方 ) his account only in respect of checks drawn by himself. He gives the bank specimens of his signature, and there is a very firm rule that the bank has no right or authority to pay out a customer’s money on a check on which its customer’s signature has been forged. It makes no difference that the forgery may have been a very skillful one the bank must recognize its customer’s signature. For this reason there is no risk to the customer in the practice, adopted day banks, of printing the customer’s name on his checks. If this facilitates forgery, it is the bank which will lose, not the customer.
When you have a bank account, you ______.

A:must always be in credit B:can’t draw any money if you’re overdrawn C:can draw money without notice D:can’t pay money to anyone else

Passage Four

A:must always be in credit B:can’t draw any money if you’re overdrawn C:can draw money without notice D:can’t pay money to anyone else