To avoid on how to use the word, you’d better refer to a dictionary.
The program, __________ at improving the students' ability of listening and speaking, will surely be a success.
He didn't answer, with his gun __________ at David.
Teachers are now aware of the difficulty that some students have __________ attention.
—I made it at last. I am on top of the world!— __________
Liu Xiang trained hard before the Asian Games in Guangzhou, and it __________. He won the gold medal in 110 meters' hurdles.