连锁店客房每间每年的检查保养频率为（）次。
A.1至3
B.2至4
C.3至5
D.4至6
参考答案：D
They are developing new types of plants that can be grown in poor soil or even sand,and that are
less to be attacked by pests and diseases.
A.possible
B.probably
C.likely
D.maybe
110kV送电线路导、地线各相间弛度相对误差应不大于（）mm。
A、100；
B、200；
C、300；
D、400。
