逐渐加入糖，一次大概加1大勺，继续打发到硬性发泡。

Gradually add sugar, about 1 TBSP at a time, beating until stiff peaks form.

youdao

蛋清用打蛋器打成粗泡，可以加一点点白醋或柠檬汁，并且将50克白糖分三次加入，打发成硬性发泡。

Use a mixer to whip the egg whites, add a few drops of lemond juice or white vinegar, then add the 50g sugar in 3 additions, whip until stiff peaks form.

youdao

蛋清用打蛋器打成粗泡，可以加一点点白醋或柠檬汁，并且将50克白糖分三次加入，打发成硬性发泡。

Use a mixer to whip the egg whites, add a few drops of lemond juice or white vinegar, then add the 50g sugar in 3 additions, whip until stiff peaks form.

youdao