单项选择题
Our heavy derrick has been （）(不用)for a long time.
A. out of order B. out of date C. out of danger D. out of use
单项选择题 （）(调高) the derrick, please.
单项选择题 （）(降下)the derrick, please.
单项选择题 Before the operation of the derrick, check all （）(索具)closely and everything must be in good condition.
