ⅰ.单项填空 1.—what are those on the________? —the________ that have fallen off the big trees. a.roofs;leaves b.rooves;leaves c.roofs;leafs d.rooves;leafs 2.she always differs________ me________ how to spend the vacation. a.on;with b.with;on c.at;with d.from;in 3.he undertook________ the working conditions. a.improving b.being improved c.to improve d.to be improved 4.tom,jack and rose were named as assistant professors.believe it or not,________ three of them were of ________ age. a./;an b./;the c.the;an d.the;the 5.i was about to give up my effort to work on the puzzle when a good idea________ me. a.beat b.struck c.attacked d.caught 6.—mom,may i play the computer games for a while? —________!dad is in the study. a.help yourself b.it’s up to you c.behave yourself d.go ahead