... 4,000 years, is one ofmankind's first inventions.a. howb. whenc. whichd. about > c 120. children master the basics, advanced development becomeseasier.a. Theb. Oncec. Thatd. Even ... much surprised me when he said he was loving me.a. very muchb. mec. saidd. was loving > d 20. Throughout his speech, the boys were deeply attention.a. Throughoutb. speechc. deeplyd....