We are _______ at the rapid progress Mark has made in this semester.
C
暂无解析
Itisnot---_______formetoreturnallthebookstothelibrarynowbecauseIstillneedsomeofthemformyresearch.
Heworksinouruniversityasavisiting_______,notasaformalfacultymember.
Thisriverissobigthatitisimpossibletobuilda_______underitwithoutmoderntechnology.