[单选题]利用仰卧压胸人工呼吸法抢救伤员时,要求每分钟压胸的次数是( )
A..8~12次
B..16~20次
C..30~36次

Stressful working conditions lead to a breakdown in group co-operation which can damage effectiveness and productivity, a study has found. Psychologists have discovered that when employees work in crisis (21) they are less willing to work together. The study showed that when workers are under stress, they have a strong (22) to concentrate on their own personal (23) to the detriment of their colleagues.
In the study, 100 naval personnel worked in groups of three, and each group was given a computer (24) of a naval decision-making task. Under a high (25) of stress, they had to monitor a radar screen with their own ship at the centre and numerous unidentified contacts around the ship.
As (26) participants operating in this highly stressful situation performed worse than those operating under normal circumstances. But the results also showed that under stress,
A. focus
B. area
C. direction
D. point

In June 1985, two British mountaineers Joe Simpson and Simon Yates made the first-ever climb of the 21,000-foot snow-covered Siula Grande mountain in Peru. It was an exceptionally (26) job, but nothing compared to what was to (27) . Early in the process, Simpson (28) and broke his right knee. Yates could have (29) him but managed to find a way of (30) him down the mountains on a rope in a series of difficult drops. Then Simpson fell into a crevasse and Yates eventually had no (31) but to cut the (32) , completely convinced that his friend was now (33)
In his book on the (34) , Joe Simpson wrote:
(35) I looked at the distant moraines, I know that I must at least try I would probably (36) there among those rocks. If I died, well, that wasn’t so (37) , but I wouldn’t have (38) waited for it to happen. The (39) of dying no longer affecte
A. common 
B. evident 
C. extraordinary 
D. lucky