In space,______and equipment need many forms of protection.A．pilotsB．astronautsC．engineers

_____ is the circulation and refreshing of the air in a space without necessarily a change

In 1978 the united States National Air and Space Administration selected Sally Ride______

Some grasses and flowers can survive in the desert because ______.A．the need little water

Physicians need ______ expertise in pain and symptom management and skills in communicatio

Five hundred years later, the need for increased trade and an error in navigation______to

Equipment and technology upgrades do not______ solve the problem either.A．virtuallyB．rarel