Only after one has become a parent _____ how great his parents are.
Although you can’t sense the dangers of drinking heavily now, but ________ you may develop high blood pressure.
He ________ goes to the National Library of China, once a month at most.
It ________ we had stayed together for a couple of weeks ________ I found we had a lot in common.
Dick made a phone call to his wife, ________ was certain about where the car key was.
The president took immediate steps ________ the improvement of the poor’s living conditions.