he was investigating ways to improve the telescope, Newton made_______discover which completely changed______ man’s understanding of colour.

(2013·江西，28)She says that she’ll have to close the shop ________ business improves.

The problem is difficultfor me work out.

The professor________his thoughts before giving his lecture，so that he could make himself understood well.[ ]

Li Hai，___ you speak Chinese -Yes，but only a little