从方框中选择合适的单词并用其适当形式填空。art, there, student, come, thing (1) — Where is Jack's schoolbag?— Look! It's . (2) Your parents can to our school library. (3) Some and a teacher are in the classroom. (4) Mr. Yang is an teacher. (5) Those are in the bookcase. 答案:【1】there
【1】come
【1】students
【1】art
【1】things如图所示,一束单色光从一折射率为3的平板玻璃砖的上表面A点以60°入射角射入,经过时间t1穿过玻璃砖从下表面射出.若把玻璃砖取走,该单色光将通过B点,且从A到B的时间为t2.则t1与t2比较,正确的是( )A.t1>t2B.t1=t2C.t1<t2D.以上情况都有可能