head down to 朝著...去:down是副詞,to是介詞,因?yàn)楦痹~后不可以接名詞,所以后面再加介詞后才能接名詞.以下 四個(gè)詞組都屬于：動(dòng)詞+副詞+介詞 的結(jié)構(gòu)例如：
They headed down to the foot of the mountain.他們朝著山腳下進(jìn)發(fā).
At last they lay down under the tree and had a rest. 最后,他們?cè)跇?shù)下躺下來(lái)休息.
Don't look down upon people who are not as rich as you. 不要瞧不起那些不如你富有的人