61. learn / know sth by heart 背诵,牢记在心 62. help oneself to sth / cannot help doing sth / cannot help to do sth 随便吃/ 禁不住做某事/ 不能帮忙做某事 63. hold on / hold up 坚持,稍等/ 阻塞 64. insist on / persist in / stick to 坚持 65. knock at t...