“How long have you been watching

“How long have you been watching "How long have you been How long have you been skating? how long have you been playing basketball ? How long have you been swimming? How long have you been ____? 1.How long have you been here? how long have you been ---work? how long have you been 用法 How long have you been in China? How long have you been studying English? How long have you been working here?