Ⅰ.单句语法填空
1．The difference of spelling between American English and British English is often puzzling(puzzle)．
2．Yesterday witnessed(witness) the traffic accident occurring on the highway.
3．Several years ago scientists assumed(assume)there was no animal life on Mars.
4．His sudden disappearance(disappear) has puzzled the police for a long time.
5．As the sky is rather dark, there is no doubt that there is a good possibility(possible) of rain tonight.
6．It must be evident(evidence) to all of you that he has made a mistake.
7．There are two new houses under construction(construct)．
8．In some developed countries, it is against the law to dismiss(dismiss) a worker without reason.
