How long have you been working here?

How long have you been working here? Have you been working here long?"long"是什么词性. 1.How long have you been here? How long have you been here? how long have you been here 和 how long have you stayed here hello!i___you ___in London .how long have you been here? --how long have you been here in sydney?--____last wednesday 求教How long have you been living here Hello!I__you___in Tokyo.How long have you been here? "How long have you been Hey,I 【】to meet you here .How long have you been here? How long __ you __(从事)the project?为什么答案是have,been working on