【单选题】When I entered the room, I saw him____ at the picture in front of the classroom. [ ]
【单选题】When I entered the room, the boy was in the TV series Journey to the West.
【简答题】When I entered the room, I found the cup (break) ________ on the table.
【单选题】He was cleaning his room when I entered the house. =His room _____ by him when I entered the room.
【判断题】河豚毒素是一种毒性很强的神经毒,毒性的产生主要是因为这种毒素是具有高选择性的钠离子通道的阻断剂。