Blackholes
问题详情:
Black holes _____ not be seen directly, so determining the number of them is a tough task.
A. can B. should C. must D. need
【回答】
A
知识点:情态动词
题型:选择题
问题详情:
Black holes _____ not be seen directly, so determining the number of them is a tough task.
A. can B. should C. must D. need
【回答】
A
知识点:情态动词
题型:选择题