By the time he was twelve he ______ a chemistry lab of his own.
Rather than _______ on a crowded bus, he always prefers ______ a bike.
________ I came, the city wasn’t so beautiful.
Where and when to go for the holiday still ______.
It is usually warm in my hometown in March, but it ______ be rather cold sometimes.
Please put the bottle on the top shelf, out of the children’s __________.