____some doubt among scientists about the cause of cancer.

I preferred _______the long jump rather than ________ in the relay race in the school sports games.

. The meeting was about to end and everyone was in a hurry to leave when Ted insisted_____ Some questions.

—— How did you pass the challenging test?—— It was a long time       I found a series of suitable methods.

There is _______ in persuading him when he turns a deaf ear to you.