题目内容
You cannot go without a pencil when writing or drawing something. You have probably noticed letters H and B printed on your pencil. What, for example, do HB, 3H and 3B mean?
Those are letters showing the hardness or the lead(铅) or graphite(石墨) in a pencil. H refers to hard lead, The bigger the Arabic number before the letter H, the harder the lead, and the lighter will be the colour. The hardest pencil has 6H on it. Such pencils are often used in making engineering drawing. People seldom write with them. B stands for soft lead. The bigger the number before the letter B, the softer the lead, and the darker will be the colour, the softest being the 6B pencil. Such pencils are used by artists.
The HB pencil has a lead core(芯) that is neither too soft nor too hard. Its colour is medium(中等的) in its blackness. It is most suitable for ordinary writing and drawing.
1.6H pencils are often used by ________
A. students B. engineers C. artists D. writers
2.A 4B pencil is ___________than a 3B-one.
A. harder B. better
C. more expensive D. softer
3.The best title for the passage would be "________ "
A. Pencils
B. Hard pencils and soft pencils
C. Letters H and B
D. Symbols(符号) on your pencil