第四用英语简写怎么说

"第四" can be abbreviated as "4th" in Engpsh.

For example, you could say "The 4th item on the pst is the most important one." This means that the fourth item on the pst is the most important one.

Note that when abbreviating numbers in this way, it is common to use the ordinal form of the number. In this case, "4th" is the ordinal form of the number four, which indicates that it is the fourth item in a series.