keep still保持靜止/別動;
as usual和往常壹樣;
further one's study 繼續學習深造;
in one's opinion 依某人看來;
switch on接通,打開(旋鈕)之類的;
figure out合計為, 計算出, 解決, 斷定, 領會到;
stand for 代表;
wear and tear 磨損;
insert .... Into......把。。。。插入到。。。中