题目

单句改错 The number of people present at the concert was much more than expected．There were many tickets left． 答案：答案：解析： much more→much smaller9．检查装置的气密性时，把导管的一端浸入水中，用手紧握试管，若水中导管口有气泡冒出，把手移开，过一会儿后导管内形成一段水柱，说明装置气密性良好．