Correct

使不了

/ shǐ bùle / 
Strokes

Example

As a Verb

cannot use; be unable to manage

1
Háizi
孩子
hái
还
xiǎo
小
  
,
shǐ
使
bù
不
le
了
jìsuànqì
计算器
  
。

The child is still too young to use a calculator.