1 . 那些燃烧煤的工厂也用大量黑烟污染了空气。
Factories that ______ ______ also polluted the air with a lot of ______ ______.

2 . People used to                sky lantern when they were in trouble. But today, people               the lanterns and watch them rise into the sky with their wishes.

A．send up; lit

B．send out; light

C．send for; burn