当三相负载对称时,三相电路的功率等于()倍的单相功率。
A.0.5
B.1
C.2
D.3
参考答案:D
(每空2分,共8分).将4 g NaOH溶于_________g 水中,可使溶液中H2O与Na+的物质的量之比为20:1,此溶液中溶质的质量分数为 ;若测得该溶液的密度为1.1 g·cm-3,则该溶液体积为 (精确到小数点后1位),溶液中c(Na+)为_________(精确到小数点后2位)。
(2013·正定中学二次月考)Some passersby witnessed the car accident ________ five passengers were killed,a baby included.
A.in which
B.which
C.that
D.in that