helped helps help I can______you with your math She often_____me with my math She_____me with my ma

I can______you with your math -------help
can+动词原形 can 是情态动词,should,must,would,could等均是此类用法.
She often_____me with my math ------helps
she 第三人称单数,动词加s
often:经常发生的,惯常动作.所以用一般现在时.
She_____me with my math.----------helped
鉴于你的三个选项,排除后,就选helped,表示过去发生的事,用一般过去时.但是它也可以填 helps.