又来麻烦你了.我现在初三,初二英语没好好学.有些东西不懂.

您好!

英语中按动词后可否直接跟宾语,可把动词分成及物动词和不及物动词.
及物动词（vt.）,顾名思义,就是可以+物（就是宾语啦）的动词.
比如：
see +sth ,他就是及物动词啊.
hear+sth 这也是,如此类推即可.
当然也有一些又是及物动词,有事不及物动词,这样的词语就不用管他,只要记住固定词组就好.
例如：talk sth talk to sb,这样的词很灵活的
不及物动词（vi）：就是后面不能直接+宾语的,要通过介词（of,to,for等）才能+宾语.
比如：look at sth,必须要有at才能加sth,否则就是错滴.

至于什么时候用现在完成时：
for + 时间段；since + 时间点
They have lived in Beijing for five years.
They have lived in Beijing since 1995.
I have learned English for ten years. 这样的句子要用现在完成时.

常见的不确定的时间状语：lately; recently, just, already, yet, up to now; till now; so far, these days, Has it stopped raining yet ?
这也是现在完成时的标志.
考点三：在表示“最近几世纪/ 年/ 月以来……”时间状语中,谓语动词用现在完成时. in the past few years/months/weeks/days；over the past few years; during the last three months; for the last few centuries, through centuries; throughout history 等 考点四：表示“第几次做某事,”或在 “It is the best (worst, most interesting ) +名词 ＋that” 后面跟现在完成时. This is my first time that I have visited China. This is the most interesting film I have ever seen. That is the only book that he has written.