【单选题】
<img title=无标题.jpg alt=无标题.jpg src=https://huaweicloudobs.ahjxjy.cn/FEA630E4A29C8297FA52F7F8C1541FFB.jpg/>
①
<img class=jc-formula style=vertical-align: middle; src=https://huaweicloudobs.ahjxjy.cn/A69A8A8E03B543F42881BE1FECF1D22F.png data-tex=I=14.14mA,i=20sin(1000t+{ 45 }^{ 0 })mA/>
②
<img class=jc-formula style=vertical-align: middle; src=https://huaweicloudobs.ahjxjy.cn/61A79C8AA26A0B2C1204D4815BE900D6.png data-tex=I=14.14mA,i=20sin(1000t-{ 45 }^{ 0 })mA/>
③
<img class=jc-formula style=vertical-align: middle; src=https://huaweicloudobs.ahjxjy.cn/76C2FE44ED64E707C4F6D00421095DAE.png data-tex=I=20mA.i=20sin(1000t+{ 45 }^{ 0 })mA/>
④
<img class=jc-formula style=vertical-align: middle; src=https://huaweicloudobs.ahjxjy.cn/C45DCC8EC5DFF29788D659A0E3D310BC.png data-tex=I=14.14mA,i=14.14sin(1000t+{ 45 }^{ 0 })mA/>