When you speak English, or any language, think about phrases and not individual words. Pay attention to the rising and falling tones and the ways in which sounds change to help join words together.
When we speak naturally each word effects the next word. Fluent speech flows. To make speech flow we change the end and beginning of some words depending on the sounds. In English there are different ways that words change when they join together in a sentence.
Consonant to vowel linking
when the first word ends with a consonant sound and the second word begins with a vowel sound.
Vowel to vowel linking
when certain vowels come next to each other an extra sound is added to make the link smooth.
The linking 'r'
In standard British English (Rp) the letter 'r' after a vowel sound at the end of words is often not pronounced. However, when the following word begins with a vowel the /r/ sound is pronounced to make a smooth link.
When the sounds /t/ or /d/ occur between two consonant sounds, they will often disappear completely from the pronunciation.
Connective -r- examples
Sounds join together
When a word ends in a consonant sound and the following word begins with the same consonant sound, we don't pronounce two sounds - both sounds are pronounced together as one
When a word ends in a consonant sound and the following word begins with a consonant sound, depending on the particular sounds, the last sound of the first word or both the last sound and the first sound of the next word can change
Sounds twinning (gemination)
When a word ends in a consonant sound and the following word begins with the same consonant sound, we don't pronounce two sounds - both sounds are pronounced together as one.