Some teenagers _______ their health because they often expose themselves to so many electric products.
It was in the small house ___ was built with stones by his father ___he spent his childhood .
If better use is ____ your spare time , you will make greater progress.
— Did you call on any of your old friends when you returned to your hometown ?—______ of them . They were all very busy .
It took seven years __________ they finally got married.
The students asked me ____________ going to be held.