1. The hijackers threatened to explode the plane. (x)
The hijackers threatened to blow up the plane. (√)
explode是指炸弹的“爆炸”或“引爆”，如:The bomb failed to explode.(这枚炸弹没有爆炸。) “炸掉某物”须用 blow up sth。
2. Whenever you feel the blue, try singing a song.(x)
Whenever you feel blue / get the blues, try singing a song. (√)
“感到忧郁”的正确说法是feel blue或get the blues。
3. There is a doctor on board of the plane.(x)
There is a doctor on board the plane. (√)
on board=aboard，可作介词使用， 其后直接接交通工具即可。
4. Our school boasts of a library of 200,000 volumes.(x)
Our school boasts a library of zoo,ooo volumes. (√)
boast of / about sth是“吹嘘某事或某物”，通常以“人”作主语，如:He always boasts of his swimming skills.(他总是吹嘘自己的游泳技能。)boast sth是“以拥有某物自豪”，常以“地方”作主语。
5. Her behavior completely boggles me.(x)
Her behavior completely baffles me. (√)
Her behavior completely boggles my mind. (√)
baffle sb 或 boggle sb's / the mind 是“使某人无法理解”的意思，为固定用法。
6. I know from the bottom of my heart that my brother was framed.(x)
I know in my bones that my brother was framed. (√)
I know deep down that my brother was framed. (√)
from the bottom of sb's heart=sincerely，是“诚恳地”或“由衷地”的意思，如:I thank you all from the bottom of my heart. (我由衷地感谢你们大家。)指某人对某事“心知肚明”，须用know deep down 或 know in sb's bones (that)…。
7. The flight is already fully ordered. (x)
The flight is already fully booked. (√)
order是“订购”或“点菜”的意思，如:The model is out of stock, but we can order one for you.(这个机种目前缺货，不过我们可以帮你订一台。) 订机位或侯厅须用book。
8. The boundary has been a bone of contention between the two countries.(x)
The border has been a bone of contention between the two countries. (√)
boundary通常是指“州/县界”，“国界”用border。
9. I was born in a single-parent family.(x)
I was born into a single-parent family. (√)
be born in + 地方/年代，如:My younger sister was born in Tokyo in 1980。(我妹妹于1980年在东京出生。) be born into + 特殊的家庭。
10. He was born an athlete.(x)
He was a born athlete. (√)
He was born an athlete.意为“他出生时就是运动员。”这显然不合理。He was born to be an athlete.(他出生就注定要当运动员。) 这较合理。He was born an orphan.(他生下来就是孤儿。)这也合理。a born athlete / musician / artist 是强调 “某人天生就是一块运动员/音乐家/艺术家的料”。