The Tibetans have lived in the Himalayas for centuries and have adjusted to the conditions _________.

A．at such great height

B．at such a great height

C．on such great height

D．on such a great height

(二) 建筑工程施工安全技术

搅拌机在使用前要空车运转，检查各机构的离合器及制动装置隋况，不得在运行中( )。

A．用工具进入搅拌筒内扒动

B．将手伸进料斗内

C．做注油保养

D．切断电源