可不可以说：He is taller than I am

than在这里是用作介词的,用于二者比较也是一般用介词形式,当然,than也作连词,举例吧,The cost of the repairs was a lot cheaper than I thought.但多数情况than 的连词形式用于would rather/sooner...than...宁愿...而不愿...,hardly/scarcely/no sooner ...than...一...就.作连词也可用在than表示“除...之外”They left me with no option than to resign.
另外,是主语的比较.He is taller than me.主语是he所以用me.