If the latest date of shipment is April 15，2009，the goods should be shipped____． A: after April 15 B: on or before April 15 C: between April 10 to April 20 D: on April 20

What day is Earth Day? A: 22nd, April B: 25th, April C: 23th, April D: 26th, April

Earth Day falls on ______. A: April 22 B: April 22, 1970 C: April 22, 1990 D: Sunday, April 22

4月21日的正确读法是?(多选)()(5.0分)A.()April()twenty()one()B.()April()twenty()first()C.()The()twenty()one()of()April()D.()twenty()first()of()April()E.()the()twenty()first()of()'()April

已知三阶矩阵$A$满足$\mid A-E\mid=\mid A-2E\mid=\mid A-3E\mid=0$，则$\mid A\mid$=( )。 A: $4$ B: $6$ C: $12$ D: $3$

中国大学MOOC: (April 24th /April 22ed) is the Earth Day every year?

设$A,B$是$n$阶正交矩阵，且$\mid A\mid=-\mid B\mid$，则( ). A: $A+B$可逆 B: $A+B$不可逆 C: $\mid A+B\mid=1$ D: $\mid A+B\mid=-1$

In our email of April 20th, we make ________ clear that shipment be effected before April 28th.

___ is a very important date，from which CIQ is mergered with China Customs and new China Customs come into being. A: April 20，2018 B: April 2，2018 C: April 12，2018

Songkran falls in mid-April every year, and has its origins in ancient and the position of the . A: astrology B: sun C: agriculture D: moon