$#Cam$
` -> ` Cấu trúc thì HTTD
` -> ` S + be + V-ing
` -> ` S + be not + V-ing
` -> ` Be + S + V-ing
` 1` is sitting - are talking
` -> ` DHNB : now
` 2 ` : are running
` -> ` DHNB : at the moment
` 3 ` : is riding
` -> ` DHNB : now
` 4 ` : aren't working
` -> ` DHNB : right now
` 5 ` : is swimming
` -> ` DHNB : at the moment