W: GPG error: http://apt.newrelic.com newrelic Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B31B29E5548C16BF
W: Failed to fetch gzip:/var/lib/apt/lists/partial/ppa.launchpad.net_yannubuntu_boot-repair_ubuntu_dists_precise_main_i18n_Translation-en%5fUS Encountered a section with no Package: header
W: Failed to fetch gzip:/var/lib/apt/lists/partial/ppa.launchpad.net_yannubuntu_boot-repair_ubuntu_dists_precise_main_i18n_Translation-en Encountered a section with no Package: header
W: Failed to fetch gzip:/var/lib/apt/lists/partial/apt.newrelic.com_debian_dists_newrelic_non-free_i18n_Translation-en%5fUS Encountered a section with no Package: header
W: Failed to fetch gzip:/var/lib/apt/lists/partial/apt.newrelic.com_debian_dists_newrelic_non-free_i18n_Translation-en Encountered a section with no Package: header
W: Failed to fetch gzip:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_i18n_Translation-en%5fUS Encountered a section with no Package: header
W: Failed to fetch gzip:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_i18n_Translation-en Encountered a section with no Package: header
E: Some index files failed to download. They have been ignored, or old ones used instead.
我执行了“sudo apt-get clean”...仍然遇到同样的错误。请帮我解决这个问题。