ch是什么意思

ch

ch: digraph used in Old French for the "tsh" sound. In some French dialects, including that of Paris (but not that of Picardy), Latin ca- became French "tsha." This was introduced to English after the Norman Conquest, in words borrowed from Old French such as chaste, charity, chief (adj.). Under French influence, -ch- also was inserted into Anglo-Saxon words that had the same sound (such as bleach, chest, church) which in Old English still was written with a simple -c-, and into those that had formerly been spelled with a -c- and pronounced "k" such as chin and much.

As French evolved, the "t" sound dropped out of it, so in later loan-words from France ch- has only the sound "sh-" (chauffeur, machine (n.), chivalry, etc.).

It turns up as well in words from classical languages (chaos, echo, etc.). Most uses of -ch- in Roman Latin were in words from Greek, which would be pronounced correctly as "k" + "h," as in blockhead, but most Romans would have said merely "k." Sometimes ch- is written to keep -c- hard before a front vowel, as still in modern Italian.

In some languages (Welsh, Spanish, Czech) ch- can be treated as a separate letter and words in it are alphabetized after -c- (or, in Czech and Slovak, after -h-). The sound also is heard in more distant languages (as in cheetah, chintz), and the digraph also is used to represent the sound in Scottish loch.

3. FT - IR shows DLC film comprises CH 3、 CH 2、 CH 、 Si - O - Si , Si - O - C and Si - CH 3 bond.: 通过FT-IR分析研究表明:薄膜中含有CH_3、CH_2、CH、Si -O-Si,Si -O-C 和Si-CH_ 3等化学键.