This chair can't bear someone so heavy sitting on it.
Tips
grammar
禁不住 is a potential complement (V不住). It has two meanings: 'can't restrain oneself from' (禁不住笑) and 'can't withstand' (禁不住重压). Context makes the meaning clear.
mistakes
The 禁 here is pronounced jīn (1st tone), not jìn (4th tone). Many learners use the wrong tone because 禁止 (jìnzhǐ) is more familiar.
