Explain the aspects of connected speech (rhythm, assimilation, liaison).

The aspects of connected speech are elements we take for granted in everyday life, but which are actually fundamental to our understanding of the spoken word.
Rhythm is defined as a sound that happens at regular intervals. In the context of speech, the rhythm of speech is the pattern of beats, or the intervals at which syllables are stressed in a sentence. This is particularly notable in poetry, where the "feet" of a line (iambs) helps it contribute to the cohesion of the poem as a whole. For example, with the stressed syllables in capital letters, we can see how the rhythms of these two lines are identical:
HE inVENted MODern LIFE
THEN he FOUND it FULL of STRIFE
Assimilation is when a phoneme takes on certain characteristics based on the sounds occurring on either side of it. This can happen either way around in a word. For example, "Th" is pronounced differently in "That" to in "thin." It is affected by the sounds following it (regressive assimilation.) In progressive assimilation, a phoneme is affected by the sounds preceding it. For example, the "s" sound in "those" is different to that in "this."
Liaison, or linking, is the phenomenon by which the end of one word is naturally connected to the beginning of the next. An excellent example is the way the phrase "law and order" is generally pronounced as one word, "laanorder." Other examples might be "first time" (usually pronounced "firstime") or "this song" ("thissong.") Effectively, in liaison, a consonant does double duty between two words, although theoretically it should be repeated.