.tend既可以做及物动词,也可以作不及物动词.
tend后面的确可以加不定式做其宾语,此时tend视为及物动词.
再比如agree是不及物动词,但是它也可以加不定式或宾语从句做其宾语,即：agree to do sth 或 agree + that从句,此时它视为是及物动词.
2.tend to do sth意思是“往往会/倾向于/易于做某事”.
如：My grandmother tends to go to bed early every day.
He tends to be angry when others disagree with him.
3.一般没有tend to doing sth的结构,只有tend to sth.
tend to sth/sb一般翻译为“往.../朝向...”/“照料/伺候...”/“留心/注意...”.
如：I tended to the left,but saw nothing.
tend解释为“倾向于”的时候,是不及物动词,但是用作“倾向于做什么”的时候,可以看成是及物动词.