She told me the sun ______ in the east.
A:rise
B:rose
C:rises
D:had risen
⑴____ A. other B. ocean C. so
⑵____ A. throw B. snow C. how
⑶____ A. thousand B. south C. mouth
⑷____ A. smoke B. those C. close
一质点做简谐运动,其位移x与时间t的关系图象如图所示,由图可知,在t=4s时,质点的( )