. Trade tests; the scientific measurement of trade proficiency . PICTURE 3 5. Q. Why is the operation in that picture necessary? A. (i) Expansion and contraction. (2) Crack. (One sufficient). PICTURE 4 6. Q. What kind of pre-heating is being used there?A. Charcoal. 252 TRADE TESTS

---

Size: 1987px × 1258px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: ., bookcentury1900, bookdecade1920, booksubj, booksubjectoccupations