Ⅰ.单句语法填空
1．For miles around me there was nothing but a desert，without a single plant or tree ________ sight.
2．Obviously，students are terrible at ________ (adjust) their sleep cycles to their daily schedule.(2014·四川，阅读D)
3．After a week，the two groups switched ________ participants.
4．Reviewing the video monitor afterwards，they noticed two armed men with their faces covered by masks step out of a carriage and slide ________ the bank through the backdoor.
5．The university wants its undergraduates to take ________ a regional language，if time permits.
