Usually, the more syllables a sentence has the longer it takes to say it. It is true for most of the languages, but it is not the case for the language of English.

English is a stress-timed language, the number of stressed syllables in a sentence affects the time the speaker uses to say the sentence. People tend use more time to say the stressed syllables, they utter the stressed syllables clearly and in a louder or longer voice, but not for the unstressed syllables or words.

The more the stressed syllables a sentence has the longer time it takes for the speaker to say it. The unstressed syllables contribute less to the time used, and people usually reduce it and sometimes omit it completely in uttering a sentence.

Comparatively speaking, Chinese is a syllable-timed language, each syllable receives the similar amount of time to say it, thus, it makes sense to say that the longer a sentence looks in writing the longer it takes to say a Chinese sentence, which is a syllable-timed language.

Thus for us, the Chinese language speakers, we should pay much attention to this stress-timed feature of English, and avoid saying every word (or syllable) of English in the same weight and strength, and put emphasis only on the stressed syllables or words (content words) and reduce the unstressed syllables or words (the so-called form words, or function words) unless they are required to emphasize, and thus, create the melody of English so that we can be understood or we can understand better.

As an example of the stress-timed feature of English, the following is a series of sentences, and the sentences have three words that are the same. We have ‘dogs’, and we have ‘eat’ and we have ‘bones’.  The sentences get longer and longer as you look at them, at least in the writing because more syllables are added with each sentence. However, each sentence takes just about the same amount of time to say as the shorter one before it. In fact, it takes approximately the same amount of time to say the first and the last sentence:

Dogs eat bones.
The dogs eat bones.
The dogs eat the bones.
The dogs will eat the bones.
The dogs will be eating the bones.

Below is an interesting picture demo of stress-timed and syllable-timed language: