You should make an apology _____ your mother ______ your rudeness.
— What on earth are the police busy with?— They have been looking into how the plane crash _______.
It is _________ to increase input in areas of innovation to ensure the country's promising prospect.
— May I ask for two days off tomorrow?—______. You know, the National Day holiday is just around the corner and every salesgirl is as busy as a bee.
It was nine years ago, ________ I went to the UK for the first time, ________ I began to learn English.
That old man ________to be more than a hundred years old, but he looked much younger than most of the ninety-year-olds.