Many people in the west make ________ a rule to buy Christmas presents for their relatives and friends.

A．this

B．it

C．that

D．them

有关短波治疗时应该注意的事项，下列何项叙述正确

A．治疗进行中，患者可随意增加强度以满足需要
B．患者穿着尼龙合成宽松布料，以利排汗
C．装有人工膝关节部位，垫加毛巾避免过热
D．装有心脏起搏器患者，治疗强度不宜过大
E．以上说法皆错