She is often seen ______ the old woman.

The medicine takes effect in the __________ stage of treatment, but the effect declines when it is taken for several months.

There is ________work to do and the work is _______ difficult .

The boy is working harder than ever, hoping to ___the time he has wasted playing online games.

The engine of the bus was ______，and the bad weather added tothe worries of the passengers.