题目

在密闭容器中于一定条件下进行下列反应：2SO2 + O22SO3当到达平衡时通入18O2，再次平衡时，18O存在于(    )                                           A.SO2 、O2        B.SO2 、SO3         C.SO2 、O2 、SO3         D.O2 、SO3 答案：C 1. The street is_________(crowded) because the Spring Festival is over. 2. The shirt is only 15 yuan. It’s _________(expensive). 3. They want to visit the world’s ________(large) water slides. 4. There are some ________(clown) playing with children in the park.