For what purposes does a Grammar-translation teacher employ translation in teaching a foreign language?

For what purposes does a Grammar-translation teacher employ translation in teaching a foreign language?

He/She intends to use translation to present a new grammatical item/rule, to enable the students to understand a new passage or to assign as exercises at the end of a lesson.
全题共5分,答案含三点,第一、二点2分、第三点1分。如表述有语法、拼写、标点等问题,酌情扣分,但全题在这方面的扣分不得超过1分。