The most common shielding gases used for these main arc welding processes include argon (Ar), helium (He), carbon dioxide (CO2) and oxygen (O2). While Ar, He and CO2 may be used by themselves (i.e. 100%) for certain applications, in other cases the four gases are mixed together in different combinations to form shielding gas blends.
Cluster reduction in speech is when a consonant cluster, that is two or three consonants occurring in sequence in a word (like ândâ in friend), is reduced by a child into a single consonant through omission.
When two consonants appear at the end of a word (for instance the st in test), they are often reduced: the final t is deleted. This happens, to some extent, in every variety of English including standard ones. In AAVE the consonant cluster is reduced variably (i.e. it does not happen every time) and systematically.