— By asking the teacher for help.通过向老师寻求帮助。

点拨：①{#blank#}1{#/blank#}意为"为……而学习"。for为介词，意为"为了"，表示目的。

如：我为人民而学习。   {#blank#}2{#/blank#}

②by 为介词，意为"通过……方式"，后接名词，代词或动名词。

如：她通过听英语新闻来学习英语。 {#blank#}3{#/blank#}

 His father is a leader of {#blank#}1{#/blank#}.

Why not {#blank#}1{#/blank#}this war {#blank#}2{#/blank#} {#blank#}3{#/blank#}?

He goes online{#blank#}1{#/blank#} {#blank#}2{#/blank#}three hours every day.

As time {#blank#}1{#/blank#} {#blank#}2{#/blank#} my memory seems to get worse.

Mike is {#blank#}1{#/blank#} the students {#blank#}2{#/blank#} our school.