He knew the problem was serious and promised to look into it ____ he reached office[ ]

30. The coal we use today should _____ plants and trees.

What do you think of her teaching—Great! No one teaches ____________in our school.

all Goose Pagoda in Xi’an, one of the 22 Silk Road relics located in China, _______ back in 707 during the Tang Dynasty.

(2013·江苏，16)I am always delighted when I receive an e－mail from you.________the party on July 1st，I shall be pleased to attend