Correct

口哨儿

/ kǒushàor / 
Strokes

Example

As a Noun

whistling sound made through rounded lips

1
Yòng
用
kǒushàor  
口哨儿
chuī
吹
yī
一
zhī
支
qǔzi
曲子

whistle a tune

2
Chuīkǒushàor  
吹口哨儿

whistle