New genetic strains of crops have been developed, yielding significantly higher amounts. the use of high-yield hybrid crops is called
vegetation propagation
hybridization
the green revolution
cropping

It's to know your purpose before you read something because a purpose can:

Which of these flaws does ulysses reveal while leaving the island after blinding the cyclops? a. a need for comfort b. a need for companionship c. a desire for glory d. a desire for riches

Time is not always change. time can also mean continuity, and it can mean keeping acknowledged truths in mind despite differences in circumstances. there is no better example of this in things fall apart than the retellings of the proverb about the bird named eneke, the language in both retellings is almost identical despite the length of time that has passed between their repetitions. in comparing the usages of the same proverb, achebe allows his readers to note the similarities and differences between the situations, and he them understand how this story can be applied to their own lives.