Who can give me the answer?

The second question c, ductile iron is not easy to forge, tinplate is too soft and carbon steel is easy to break.

Question 3 d

Question b, the natural magnet is ferroferric oxide.

Question 5 a, using poison

Question 6 a

Question 7 c

Having multiple choices

1)ABC, desertification is not reflected.

2)ABCD, heredity and variation

25M, if the conditions are not enough, set it to 25M in the ideal situation.

Total * * * flavor = c1/5+C2/5+C3/5+C4/5+C5/5 (/Here, just separate the numbers. The figures in front are on the table. In the back) = 5+5 * 4+5 * 4 * 3+5 * 4 * 3 * 2 *1+1= 206 species.

2π times

Abandonment date calculation

Fourth, write ↓↓↓→→→BBAA

Five, stealing the concept, the major premise and minor premise are not appropriate.

Six, 1. Copper ions and ferrous ions, or trivalent chromium ions, malachite.

2. Cut off the penis, reduce testosterone, increase body flexibility, and do not grind the penis when running.

Guo Jing and his wife are both only children and can have a second child. The first child is one, and the second child is a twin.