<<echo=FALSE, results=hide>>=
## Vowels and their quality
vowels <- rbind(
  c("i", "close front unrounded"),
  c("e", "close-mid front unrounded"),
  c("ɛ", "open-mid front unrounded"),
  c("a", "open front unrounded"),
  c("ɑ", "open back unrounded"),
  c("ɔ", "open-mid back rounded"),
  c("o", "close-mid back rounded"),
  c("u", "close back rounded"),
  c("y", "close front rounded"),
  c("ø", "close-mid front rounded"),
  c("œ", "open-mid front rounded"),
  c("ɶ", "open front rounded"),
  c("ɒ", "open back rounded"),
  c("ʌ", "open-mid back unrounded"),
  c("ɤ", "close-mid back unrounded"),
  c("ɯ", "close back unrounded"),
  c("ɨ", "close central unrounded"),
  c("ʉ", "close central rounded")
)

## select 5 vowels
vowels <- vowels[sample(1:nrow(vowels), 5), ]

## randomly select 1 of 5 as correct
sol <- sample(c(TRUE, FALSE, FALSE, FALSE, FALSE))
ans <- rep("\\textbf{False.}", 5)
ans[sol] <- "\\textbf{True.}"
@

\begin{question}
Which of the following Cardinal vowels is the \Sexpr{vowels[sol, 2]} vowel?

<<echo=FALSE, results=tex>>=
answerlist(vowels[, 1], markup = "latex")
@
\end{question}

\begin{solution}
For an overview of the 18 Cardinal vowels see \url{https://en.wikipedia.org/wiki/Cardinal_vowels}.

<<echo=FALSE, results=tex>>=
answerlist(ans, vowels[,1], "is the", vowels[,2], "vowel.", sep = " ", markup = "latex")
@
\end{solution}

\exname{Cardinal vowels}
\extype{schoice}
\exsolution{\Sexpr{mchoice2string(sol)}}
