Engineers are ( ) to locate the source of the problem. A: endeavored B: endeavoring C: endangered D: endangering

The polluted air in the city is badly ______ the health of the residents. A: danger B: endangering C: dangerous D: dangerously

Before the machine is switched on, ensure that no one can _________ when the machine is running. A: endanger B: endangered C: Be endangering D: be endangered

Before the machine is switched on, ensure that no one can _________ when the machine is running. A: endange B: endangered C: Be endangering D: e endangered

A winner achieves his goal without hurting others or compromising his beliefs and convictions. A: changing B: endangering C: submitting D: composing