85℃定温线型缆式探测器的报警范围为（ ） A: 80≤T＜85 B: 60≤T＜80 C: 60≤T＜85 D: 60≤T＜90

指定系统在1分钟后关机，需要使用（ ）命令。 A: shutdown -s B: shutdown -t C: shutdown -s -t 60 D: shutdown -a -t 60

已知电压的有效值是220V,初相位是φ=60°,它的瞬时值表达式是() A: u=220sin(ωt+60°)V B: u=110sin(ωt60°)V C: u=110sin(ωt+60°)V D: u=220sin(ωt+60°)V

S7-200 PLC中T60的分辨率是（） A: 1ms B: 10ms C: 100ms D: 1000ms

If the customers are under 16 or over 60, they don't pay.

当空气的相对湿度φ=60%时，则其三个温度t干球温度、tw湿球温度、td点之间的关系为（）。 A: t=t=t B: t>t>t C: t< t=t D: t>t=t

A signal s(t)=3cos(20pt) (V) is quantized by a uniform quantizer, the step size of the quantizer is 0.1(V), then the minimal number of quantization level is L , the number of bits per sample is at least R , and the variance of the quantization error is T ([img=22x22]1803a28ec2869ac.png[/img]). A: L=60, R=5, T=0.000833 B: L=30, R=5, T=0.000833 C: L=60, R=5, T=0.001667 D: L=60, R=6, T=0.000833

‏A signal s(t)=3cos(20pt) (V) is quantized by a uniform quantizer, the step size of the quantizer is 0.1(V), then the minimal number of quantization level is L , the number of bits per sample is at least R , and the variance of the quantization error is T ([img=22x22]1802e166a76be1c.png[/img]).‎ A: L=60, R=5, T=0.000833 B: L=30, R=5, T=0.000833 C: L=60, R=5, T=0.001667 D: L=60, R=6, T=0.000833

某电压u的相位为（ωt60°），电流i的相位为（ωt30°），表明电压u（）电流i。

T细胞约占淋巴结内淋巴细胞总数的60%。