题目

Everywhere man has cut down forests in order to grow_____ crops，or to use _____wood as fuel or as building material. A.the;the    B.the;/     C./；the     D./；/ 答案：C估算．（1）吸烟不仅有害健康而且花钱．如果一位吸烟者每天吸一包18元的香烟，那么他每年花在吸烟上的钱大约要________元．（2）一个人在安静状态下，每分呼吸次数约16次，每次呼出或吸收空气约31.3ml．那么每分呼出或吸收的空气体积约为________ml．