单项选择题
A.Because of the bad weather.B.Because of his young age.C.Because he lost his way while crossing the ocean.D.Because he had no partner to help him.
单项选择题 房屋楼梯的楼梯段的踏步步数一般为()级。
单项选择题 A.He is down-to-earth.B.He is aggressive and optimistic.C.He is discouraged by his failure.D.He is confident about achieving a real first.
单项选择题 地下长距离顶管工程施工需解决的顶力问题,一般采取()。