______ birds use their feathers for flight, some of their feathers are for other purposes.
Once
If
Although
Because
The health security systems of many countries are undergoing considerable ______.( )
reservation
transformation
distinction
submission
This actor often has the first two tricks planned before performing,and then goes for ______.( )
whichever
whenever
wherever
whatever
Technological innovations, ______ good marketing, will promote the sales of these products.( )
combined with
combining with
having combined with
to be combined with
Taking on this challenge will bring you ______ someone who shares your interests.( )
in exchange for
in answer to
in contact with
in memory of
The outbreak of Covid﹣19 has meant an ______ change in our life and work.( )
absurd
abrupt
allergic
authentic