I can still remember that it is since the 1990’s, _____ we began to use cell phones,_______ the number of mobile users has greatly increased.
I have a lot of books, half of____ novels.
You can, ____, come to join us in the singing programme.
He came home after midnight, and____, he got drunk.
---Could I borrow your motor bike? ----Yes, of course, you____.
----Why is the boy crying there? ----Because____ his father.