4. When Mary finally got there, Tom had left an hour _____.
I do every single bit of housework ______ my husband Bob just does the dishes now and then.
The Great Wall, _____ to be the longest wall in the world, runs across China like a huge dragon.
It is widely believed among bioengineers _____ it will be possible to create life under laboratory conditions.
Teaching ___ child to cook will improve many of ___ skills that he or she will need later in life.
—Rather than ___ on a crowded bus, he always prefers ___ a bicycle.