Though ______, many laws of nature exist.
#97974
A
not having been discovered
B
having not been discovered
C
not having discovered  
D
having not discovered
推荐题目
__________ his project, the boy had to stay up late.
#92155
A
Not finishing
B
Not finished
C
Having not finished
D
Not having finished
  People at weekends go walking and _______ in the country, ________”bush”.
#97368
A
camping; called
B
camp; called
C
to camp; calling
D
camping; calling