单项选择题
The danger associated with using carbon dioxide in an enclosed space is（）.
A.frostbite B.skin burns C.asphyxiation D.an explosive reaction
单项选择题 The Agreement sha1l commence（）a satisfactory Medical Report by a doctor nominated by the Company.
单项选择题 Symptoms of sugar diabetes include（）.
单项选择题 Storage batteries should be charged in a well ventilated area because（）.
