struggle to do sth.
do one’s utmost to do sth.
15. 一系列
a series of
a range of
a string of
16. 毫无疑问,众所周知
undoubtedly
There is no doubt that
without doubt
No one can deny that
It is commonly acknowledged that
It goes without saying that
It is generally/ widely believed/ held/ agreed that 17.事实上
in fact
actually
as a matter of fact
practically
virtually
18. 为了
for the sake of
on behalf of
19. 有时
sometimes
at times
from time to time
on occasion
now and then
now and again
20. 越来越:
be increasingly + adj.,