大炮打蚊子
dà pào dǎ wén zi
cannon fire to hit a mosquito
to use a sledgehammer to crack a nut
大
dà
big; large; great
炮
pào
variant of 炮[pao4]
打
dǎ
a semantically light, transitive verb that is combined with various grammatical objects to form compound verbs and verb-object phrases with a diverse range of meanings (e.g. 打傘|打伞[da3 san3] "to hold an umbrella", 打電話|打电话[da3 dian4 hua4] "to make a phone call", 打針|打针[da3 zhen1] "to get an injection", 打手套[da3 shou3 tao4] "to knit gloves", 打氣|打气[da3 qi4] "to inflate")
蚊
wén
old variant of 蚊[wen2]
子
zi
noun suffix, as in 椅子[yi3 zi5] "chair"