Adjective complement
Definition
An adjective complement completes or develops the meaning of an adjective. It may be a to-infinitive clause, a that-clause, an if/whether clause or another structure selected by the adjective.
Examples
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I am pleased that you came.
The that-clause explains what caused the feeling.
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This machine is difficult to operate.
The to-infinitive completes the meaning of difficult.
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We were unsure whether the shop was open.
The whether clause states what was uncertain.
Complement vs. optional adverbial
Mina was happy that the plan worked.
The clause identifies the content or cause of the happiness.
Mina was happy yesterday.
The word adds time information but does not complete the adjective's meaning.
A complement is closely connected to the adjective's meaning. An adverbial adds circumstances such as time or place.
The subject may be introduced with it
With adjectives such as important, easy, likely and surprising, English often uses it as the subject and places the fuller idea later.
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It is important to check the figures.
The to-infinitive carries the main content after important.
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It is likely that prices will rise.
The that-clause states what is considered likely.
Common mistakes
I am difficult to understand this rule.
It is difficult for me to understand this rule.
Use it as the subject when the difficulty concerns performing the following action.
She was afraid that miss the train.
She was afraid that she would miss the train.
A finite that-clause needs its own subject and complete verb phrase.
Quick check
Question 1 of 3
Which sentence contains a to-infinitive complement?
To follow completes the meaning of easy.Which sentence has a complete clause after sure?
The complement clause needs its own subject Leo and the agreeing verb knows.Which sentence uses anticipatory it correctly?
The pattern is It + be + adjective + to-infinitive.Nice work — you've completed the quick check.
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