zhè / hái zi / sī xiǎng wán dùn / lǎo shī / jiǎng / le / hǎo jǐ biàn / tā / hái shì / bù dǒng

这孩子思想顽钝，老师讲了好几遍他还是不懂。

This child is mentally slow; the teacher explained several times and he still doesn't understand.