Those teachers simply failed to recognize that if Cantonese is your mother tongue you simply have more to do than (say) a Punjabi speaker, so of course you need longer to do it.

• 这些教师都未能认清一个事实：要是本身的母语是广东话，学起英文来比讲印度加语的人士，就得多花一些功夫，自然学习时间要拉长了。