关于网站建设和维护工作，下列叙述正确的有()。

Before doing any work on a hydraulic system equipped with accumulators, you should

A.drain the accumulators and purge with oxygen

B.bleed off all stored energy from the accumulators completely

C.charge the accumulators to prevent system energy loss

D.pump the hydraulic fluid into the accumulators to prevent fluid loss

A.Electric power and starting air

B.Lube oil standby pump and control air

C.Hydraulic switch and engage jacking gear

D.Motor drain and pneumatic control system power

A.clean the fittings before they are disconnected

B.Place drip pans under leaky fittings

C.Seal any cracks in lines with Permatex

D.Coat all threads with graphite oil

A．usage

B．ground

C．practice

D．manner

To: All employees

From: Jane McKinley

Date: Monday, 29 March 2007

Subject: Computer maintenance

We will be performing routine maintenance on the computer system this Friday, March 2, starting at 6 A.M. We will be restarting the main computer, which will result in a brief loss of services at some points during the one-hour maintenance.

A brief message will appear on screen five minutes before the maintenance occurs. It instructs computer users to save all data and exit all programs. After the maintenance is completed, users may resume working.

What will happen this Friday？

A．Computer services will be interrupted temporarily.

B．New computers will be installed.

C．Maintenance workers will take a break at 6 A.M.

D．There will be a computer competition held this Friday.

MEMO

To: All employees

From: Jane McKinley <mckinley@earthlink.net>

Date: Monday, 29 March 2007

Subject: Computer maintenance

We will be performing routine maintenance on the computer system this Friday, March 2, starting at 6 A.M. We will be restarting the main computer, which will result in a brief loss of services at some points during the one-hour maintenance.

A brief message will appear on screen five minutes before the maintenance occurs. It instructs computer users to save all data and exit all programs. After the maintenance is completed, users may resume working.

What will happen this Friday？

A．Computer services will be interrupted temporarily.

B．New computers will be installed.

C．Maintenance workers will take a break at 6 A.M.

D．There will be a computer competition held this Friday.

A．Look carefully before one jumps.

B．Think carefully before one makes any decision.

C．Think carefully before they make the decision to get married.

D．Take longer time to make up one's mind to divorce.

A．Look carefully before one jumps.

B．Think carefully before one makes any decision.

C．Think carefully before they make the decision to get married.

D．Take longer time to make up one's mind to divorce.