npm install express失败，求指导

npm http GET https://registry.npmjs.org/express npm http GET https://registry.npmjs.org/express npm http GET https://registry.npmjs.org/express npm ERR! Error: CERT_HAS_EXPIRED npm ERR! at SecurePair. (tls.js:1350:32) npm ERR! at SecurePair.EventEmitter.emit (events.js:92:17) npm ERR! at SecurePair.maybeInitFinished (tls.js:963:10) npm ERR! at CleartextStream.read [as _read] (tls.js:463:15) npm ERR! at CleartextStream.Readable.read (_stream_readable.js:320:10) npm ERR! at EncryptedStream.write [as _write] (tls.js:366:25) npm ERR! at doWrite (_stream_writable.js:219:10) npm ERR! at writeOrBuffer (_stream_writable.js:209:5) npm ERR! at EncryptedStream.Writable.write (_stream_writable.js:180:11) npm ERR! at write (_stream_readable.js:575:24) npm ERR! If you need help, you may report this log at: npm ERR! http://github.com/isaacs/npm/issues npm ERR! or email it to: npm ERR! <npm-@googlegroups.com>

报这些错误，不贴出来了，为什么呀？网上都这么说的 怎么我会失败呀