Lesson Twenty-one
听力部分
Dictation: Please prepare your paper and pen.

________ and _______________ contain _______ that ____________. Many of these ________ are ____ in the _________ of tobacco _______ and __________________. Nicotine _____ naturally __ tobacco and can be very _________. Each ____ of a __________________ a ___________ dose of nicotine ___________ the ____---and ___________________ for the _________. Even after _______________ nicotine, you may still ________________ smoke. If you don't want to ___ prematurely ____ a _______________ illness,______ to ____. Right away, you'll look better, feel better and ________________.