Correct

硬橡胶

/ yìng xiàngjiāo / 
Strokes

Example

As a Noun

hard rubber; ebonite

1
Yìng
硬
xiàngjiāo
橡胶
wūmiàn
屋面

vulcanite roofing

2
Yìng
硬
xiàngjiāobǎn
橡胶板

ebonite board