截至2020年底，中国已有899个国家湿地公园，并且近一半的湿地都受到各级政府的保护。

China had 899 national wetland parks by the end of 2020, and nearly half of the country's wetlands are protected by some level of government.

youdao

默克公司的疫苗临床试验研究了五年，葛兰素公司研究了将近六年半，因此还不是很清楚疫苗的保护时间能维持多久。

Merck's vaccine was studied in clinical trials for five years, and Glaxo's for nearly six and a half, so it is not clear how long the protection will last.

youdao

当研究人员解剖这些现存的易感染的小鼠时，他们发现其肠道典型的线性分泌粘液层的厚度仅为受保护小鼠的一半。

When the researchers dissected these now susceptible mice, they discovered that the mucous layer that typically lines the gut was only half as thick as in protected mice.

youdao