1.upgrade的基本意思是使当前的状况再提高一个等级。只用作及物动词,可接名词或代词作宾语。
2.upgrade可接介词to表示“提高到…标准”。

upgrade to(v.+prep.)
提高到…标准〔级别〕 raise the standard of sth to a higher level
▲upgrade sb/sth to sb/sth
The farmers have been trying to upgrade their cattle to the required standard.农民们一直在力图使他们的牛达到标准。
◇ 用于be ～ed 结构
She was upgraded to sales director.她已被提升为销售部主任。
Our legation was upgraded to an embassy.我们的公使馆升级为大使馆。

用作及物动词
▲S+～+n./pron.
We need to upgrade the pay and status of teachers.我们需要提高教师的工资和地位。
They upgraded the land by improving it with new buildings.他们以建造新楼房来提高土地的等级。