题目

The joke made by Tom made us ______, so the teacher couldn’t make himself______        A. to laugh; hearing  B. laugh; heard C. laughing; hear      D. laughed; heard 答案：下列情况下，不会引起环境污染的是 [　　] A．农业上大量使用化肥和农药 B．城市污水的任意排放 C．大量种植树木和花草 D．大力发展氢能源