—Why was Professor Johnson unhappy those days? —Can't you see it clearly? The only reason was that the theory he stuck to_____ wrong.
Just in front of our house ___ with a history of 1,000 years.
___ most of the earth’s surface is covered by water, fresh water is very rare and precious.
Some experts think that language learning is much ___ for children as their tongues are more flexible.
The parents suggested ___ in the hotel room but their kids were anxious to camp out during the trip .
We ___ our new neighbors yet, so we don't know their names.