I have two sentence like following:

  1. Preparing the raw materials.
  2. Cleaning beaker,then putting them into box to reserve.

This two sentence is similar,the gerund both is subject.But I am informed them all are ill-formed sentence due to no predicate.Is it illegal indeed?If it is,how to modify them?

  • The first one is not a complete sentence. The second one has a missing subject.
    – user178049
    Apr 14, 2017 at 23:19
  • These are not sentences, for they lack a finite verb phrase (they have non-finite verbs). They are subjectless gerund-participial clauses taken out of context. They could function as a subject, or complement of a preposition: Preparing the raw materials is the first stage in cooking / After cleaning the beaker, then putting them into a box to reserve, you should commence preparing the raw materials. Note that "preparing", "cleaning" and "putting" are not nouns; they are gerund-participle verbs as evidenced by the fact that they have direct objects.
    – BillJ
    Apr 15, 2017 at 8:31

1 Answer 1


A predicate consists of a verb and maybe objects (in traditional grammar). A simple sentence follows Subject-Verb-Object order. Your examples are simply missing a verb. The gerund is a noun form of a verb, so it cannot act as the verb in the sentence. The whole phrase (Gerund + Object) is a noun phrase.

Because you seem to have a list of instructions, those can be formulated using the imperative: "Prepare the raw materials!". The subject is implicit in this form and this isn't a real sentence.

Alternatively you can use the passive voice to form a sentence: "The raw materials are prepared". The active voice would need an additional subject to perform the activity.

Of course, the way you have written it is common, too, but that gerund form sounds odd in the second example, because you use the gerund like verbs, as if it should be a sentence. If you have a list, "then" would usually be another entry in the list ("3. Put ...").

  • Thanks for analysis of the first sentence,could you make more detailed about the second sentence?
    – yode
    Apr 14, 2017 at 23:39
  • I would look individually at the parts that are divided by the comma, remove the then, and apply the same reasoning as to the first.
    – Hector von
    Apr 15, 2017 at 0:29

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