Non-finite clauses contain an infinitive (to do), present participle (doing) or past participle (done). In these examples, the non-finite clauses are underlined.
I hope to write a best-selling novel.
Using international road signs reduces the risks when people drive in another country.
Books printed in the early days of the printing press are very valuable.

These clauses are ungrammatical on their own: they have to be part of a larger sentence, where they can function in a number of ways. In the first sentence above, the non-finite clause is functioning as the object (what I hope); in the second, it is the subject (what reduces the risks) and in the third, it is a relative clause, describing books (shortened from Books which were printed…).

The main difference in meaning is that the present participle generally has an active meaning (people use road signs), and the past participle generally has a passive meaning (books are printed).

When a non-finite clause functions as the subject of a sentence, it normally uses a present participle:
Writing in Chinese is difficult for foreign learners.
Alternatively, the clause can be replaced by it and moved to the end of the sentence. In this case, it normally uses an infinitive:
It is difficult for foreign learners to write in Chinese.


These activities practise this Grammar: