1. Infinitives as Subject (To practise is important / It's important to practise) In old English, infinitive clause can function as the subject of a sentence. |
Examples: To get a good job is ideal. To study diligently is important. To drink plenty of water is good for the body. |
However in modern English, this is not common. The usual form is to use "it" to introduce a subject and place the infinitive clause after. |
Examples: It's ideal to get a good job. It's important to study diligently. It's good for the body to drink plenty of water. |
The -ing form is also possible to use to begin a sentence. |
Examples: Driving a truck is not easy. Traveling by plane is convenient. Speaking in public is always nerve-racking. |
2. Infinitives as Subject Complements Infinitive clause can be used after "be" as a subject complement. |
Examples: Her dream is to become a famous ballerina one day. You job is to get the clients to sign the contract today. You are to inspect the condition of the plane thoroughly. |
3. Infinitives as Object Complements Infinitive clause can be used as object of verbs. |
Examples: She likes to sing when she's driving. Walter enjoy to travel abroad by himself. I prefer to shower in the morning before work. |