A great many new ideas _____at this education conference to improve the students’ study.

(2013·湖北武汉武昌区高三联考)One way to ________ species under threat of extinction—whatever the cause—is to remove them to zoos or parks and feed them there.

If you just spend your time___ gains and losses, maybe you'll get nothing in the end．

Mr. Brown’s condition looks very serious and it is doubtful if he will ________.

(2013·大连市一模)As its name ________， the Volunteer Farm relies on volunteers to weed, plant and harvest.