It is reported that between the year 1550 and 1950 about one kind of living things___each year .
Crops such as peas or soybeans put important minerals back into the soil, ______ it ready for crops that need fertile soil.
You may find it _______ that Charlie was taught to sing as soon as he could speak.
Since then, finding ways to grow more peanuts ______ his life goal.
______ with new scientific farming methods, they have been able to use less farmland thanin the past.
Only after I read the book _______ why she devoted all her life to medical work for Chinese women and children.