下面这段话有10个错误，请指出和改正：
Thomas Malthus published his "Essay on the Principle
of Population" almost 200 years ago. Ever since then,
forecasters have being warning that worldwide famine was 71_____
just around the next corner. The fast-growing population's
demand for food, they warned, would soon exceed their 72_____
supply, leading to widespread food shortages and starvation.
But in reality, the world's total grain harvest has risen
steadily over the years. Except for relative isolated trouble 73_____
spots like present-day Somalia, and occasional years of
good harvests, the world's food crisis has remained just 74_____
around the corner. Most experts believe this can continue
even as if the population doubles by the mid-21st century, 75_____
although feeding I0 billion people will not be easy for
politics, economic and environmental reasons. Optimists 76_____
point to concrete examples of continued improvements
in yield. In Africa, by instance, improved seed, more 77_____
fertilizer and advanced growing practices have more than
double corn and wheat yields in an experiment. Elsewhere, 78_____
rice experts in the Philippines are producing a plant with few 79_____
stems and more seeds. There is no guarantee that plant
breeders can continue to develop new, higher-yielding
crop, but most researchers see their success to date as reason 80_____
for hope