I'm afraid we can't come here on time.

(1)be afraid of sb / sth 害怕某人 / 某事；

(2)be afraid of doing sth. 害怕做某事。

Some children are afraid of snakes.

　 Don't be afraid of asking questions.

(3)I'm afraid + 从句， 恐怕， 担心： I'm afraid I have to go now.

(4)be afraid to do sth 害怕做某事

13. sometimes , sometime, some times , some time 的区别：

(1)sometimes 频度副词， 有时。表示动作发生的不经常性，多与一般现在时连用，可位于句首、句中或句末。

Eg: Sometimes I get up very early. ------How often do you get up?

(2)sometime 副词，某个时候。 表示不确切或不具体的时间，常用于过去时或将来时，对它用疑问词when.

Eg:I will go to Shanghai sometime next week.

------When will you go to Shanghai next week?

(3)some times 名词词组， 几次，几倍。其中time 是可数名词，对它提问用how many times.

　Eg:I have read the story some times.

　------How many times have you read the story?

(4)some time 名词短语， 一段时间. 表示"一段时间"时，句中谓语动词常为延续性动词，提问时用 How long.

Eg: How long will you stay here? ----- I 'll stay here for some time.