Correct

询问 vs 问

/ xúnwèn vs wèn / 
Strokes

Definition

询问 and 问 both Verbs, which mean “inquire; ask about; to solicit opinions or to ask about”.

Example

询问 is used in literary language, while 问 is more colloquial.
1
Xǔduō
许多
liúxuéshēng
留学生
gěi
给
zhāoshēng
招生
bàngōngshì
办公室
dǎdiànhuà
打电话
  
,
xúnwèn
询问
  
(
wèn
问
  
)
zěnyàng
怎样
bàomíng
报名
  
。

Many foreign students phoned to the admission office to inquire how to register.

2
Zhǔrèn
主任
xúnwèn
询问
  
(
wèn
问
  
)
wǒmen
我们
duì
对
xīn
新
jiàocái
教材
de
的
kànfǎ
看法
  
。

The director asked our views about the new teaching materials.

3
Wàiguó
外国
jìzhě
记者
xúnwèn
询问
  
(
wèn
问
  
)
zhè
这
wèi
位
zhōngguó
中国
guānyuán
官员
  
,
rúhé
如何
gūjì
估计
dōngnányà
东南亚
jīnróng
金融
wēijī
危机
duì
对
zhōngguó
中国
de
的
yǐngxiǎng
影响
  
。

The foreign reporter asked the Chinese official how to predict the influence of the Southeast Asia on China.

问 also means "to raise a question, to express one's solicitude, to interrogate, to intervene, etc."
In examples ① ② ③, 询问, and 问 both mean "to inquire about or to solicit opinions", so they are interchangeable.

In the examples ④ ⑤ ⑥, however, 问 means "to raise a question or to express one's solicitude, etc.", so it cannot be replaced by 询问.
4
Lǎoshī
老师
wèn
问
xuésheng
学生
shénme
什么
shì
是
bǔyǔ
补语
  
。

The teacher asked his students what is complement.

5
Qǐng
请
dài
代
wǒ
我
xiàng
向
qítā
其他
tóngxué
同学
wènhǎo
问好
  
。

Please send my best regards to the other students.

6
Duì
对
biéren
别人
de
的
lěngnuǎn
冷暖
  
,
tā
他
cónglái
从来
bùwénbùwèn
不闻不问
  
。

He shows indifference to others'life all the time.