以下检查中最有价值的是

A．外周血象检查

B．心电图检查

C．胸部X线检查

D．血气分析

E．超声波检查

Passage Four

It can be inferred that the attitude of the WHO and the British government toward the use of mobile phones is ______.

A．precautious

B．skeptical

C．approving

D．indifferent