1 . I stepped on his foot______(意外). (根据汉语提示单词拼写)

2 . Most people on this island are fishers, and ________, fishing forms an actual part of their leisure time.

A．accidentally

B．purposefully

C．obviously

D．formally

3 . When we misunderstand someone we know, even not ______, we are generally expected to apologize so as to polish up the situation.

A．initially

B．accidentally

C．sincerely

D．intentionally

4 . Mum a_________ knocked over a vase without noticing it and the water in it went all over the computer.（根据首字母填空）