Question

How long I shall stay is doubtful

Start with The.

Answer 1

The length of my stay is doubtful.
............................OR............................
The duration of my stay is doubtful.

Answer 2

The length of my stay is doubtful.

EXPLANATION:

There are 3 types of sentences. Simple, complex and compound. Simple sentences as the name indicates are the simple phrase. Complex sentences come with a subordinate clause which may be a noun, adjective or adverb. Compound sentences make the phrase into two parts and join it with conjunctions like and, but, etc.,

The given sentence is in the complex. We can change ‘long’ to ‘length’ while converting it into a simple sentence. Similarly, simple sentences can be transferred into complex sentences.

Example: I saw a wounded bird(simple) that can be changed to ‘I saw a bird that was wounded’.(complex). This is called the transformation of sentences.