I can do what I want and see who I want.

这个句子who作为融合型关系代词引导名词性关系分句之所以仍然见于现代英语，是因为see who I want 是一个所谓自由选择结构（free choice construction），作为融合型关系词，who，which，how在现代英语中只能用于自由选择结构，除此以外把这三个词用来引导名词性关系分句就不符合惯用了。在自由选择结构中，who，which，how被认为是whoever，whichever，however省略了ever。所以这个句子是正确的，因为who在此等于whoever。但在I can invite who I find to my birthday party.这个句子中，在现代英语就会认为这个句子是错误的，因为这不是自由选择结构，who不能引导名词性关系分句，应该把who改为whoever。关于自由选择结构，大家可以阅读剑桥英语语法下面论述（该书P1075）：

The free choice construction (You can do whatever/what you want)

[23] i Invite [whoever/whomever/who/whom you like].

In fused relatives like these the referent of the (overt or understood) subject of the matrix

clause is given the freedom to choose: in [i] it is for you to decide who you invite, and in

[ii] it is for Liz to choose where she goes. We have used ‘free choice’ to label one sense of

any, and constructions with any + integrated relative are very close in meaning to the

above: compare Invite anyone you like and Liz can go anywhere she wants (but see Ch. 5,

§7.14, n. 32, for a slight difference).

There is no detectable difference in meaning between the ·ever and simple forms in

this construction, and since who, which, and how can hardly occur in other kinds of fused

relative, it is plausible to see the ·ever as here omissible by virtue of being redundant: the

“any whatever” meaning is entailed by the free choice and does not have to be explicitly

expressed in the relative word. The verb in this construction belongs to a small class

consisting primarily of choose, like, please, want, wish, and is interpreted as if it had a

clausal complement – e.g. for [ii] “She can go wherever she wants to go”. Note, then, that

Sack who you like does not mean “Sack the persons that you like”, but “Sack whoever

you care to sack”. However, the distinctive syntactic property of the construction – that

of allowing certain simple forms which do not normally occur in fused relatives – is

generally restricted to the case where the clausal complement is merely implicit, so that

we have Invite who you want, but hardly ? Invite who you want to invite. Moreover, please

does not in fact license clausal complements: Go where you please, but not, in Present

day English, ∗ He pleased to go to Paris. And with like the meaning differs aspectually

from that of a construction with an infifinitival complement. I like to take the biggest

portion, for example, implies repeated taking (cf. Ch. 14, §5.6.1), whereas Take which you

like does not. There are also constraints on the matrix clause. For example, the fused

relative must follow the matrix verb: I’ll invite who you like but not ∗ Who you like I’ll

invite.