Mr. Wang told us that he would devote all the time he could spend _______ his oral English before going abroad.
They tried to prevent the damage ________ their cattle.
His father disappeared, ________ two children and never _______ from again.
Does the way you thought of ________ the water clean make any sense?
In order not to be disturbed, I spend three days _______ in my study.
He tried to ________ in Japanese.