A sunscreen with a protection factor of 30 allows you to stay in the sun without burning.

一种防护系数为30的防晒霜使你能够待在太阳底下而不被晒伤。

《柯林斯英汉双解大词典》

Often this simply enables a sunscreen with a sun protection factor (SPF) to dry clear and disappear into the skin rather than forming a white paste that takes all day to rub in.

通常这会增加防晒霜遮阳剂的防晒指数(SPF)，使防晒霜更易干，可以融入皮肤，而不是在皮肤上糊一层白，要一天时间才能吸收。

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Use a broad-spectrum sunscreen of sun protection factor 15 +.

使用防晒指数15 +的广谱防晒霜。

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They weren't cancerous, but she began using a sun-protection factor of 45 as part of her daily routine.

WSJ: The Myths of Daily Sunscreen

Look for sunglasses with an eye-sun protection factor (E-SPF) between 25 and 50, he said.

WSJ: The Crucial Years for Protecting Your Eye Health