Change "isn't" -> "is not"

chapters/annotations.tex

@@ -158,7 +158,7 @@ \subsubsection{Axis Properties}\label{axis-properties}
 end Axis;
 \end{lstlisting}
 
-When an axis bound isn't provided, the tool computes one automatically.
+When an axis bound is not provided, the tool computes one automatically.
 
 An empty \lstinline!unit! means that the axis is unitless, and each expression plotted against it may use its own unit determined by the tool.  The tool is responsible for conveying the information
 about choice of unit for the different variables, for instance by attaching this information to curve legends.
@@ -172,7 +172,7 @@ \subsubsection{Axis Properties}\label{axis-properties}
 
 If a tool does not recognize the \lstinline!unit!, it is recommended to issue a warning and treat the \lstinline!unit! as if it was empty, as well as ignore any setting for \lstinline!min! and \lstinline!max!.
 
-When \lstinline!label! isn't provided, the tool produces a default label.
+When \lstinline!label! is not provided, the tool produces a default label.
 Providing the empty string as \lstinline!label! means that no label should be shown.
 Variable replacements, as described in \cref{variable-replacements}, can be used in \lstinline!label!.
 The Modelica tool is responsible for showing the unit used for values at the axis tick marks, so the axis \lstinline!label! shall not contain the unit.
@@ -192,7 +192,7 @@ \subsubsection{Plot Curves}\label{plot-curves}
 It is an error if \lstinline!x! or \lstinline!y! does not designate a scalar variable.
 When the \lstinline!unit! of an \lstinline!Axis! is non-empty, it is an error if the unit of the corresponding \lstinline!Curve! expression (i.e., a variable's \lstinline!unit!, or second for \lstinline!time!) is incompatible with the axis unit.
 
-When \lstinline!legend! isn't provided, the tool produces a default based on \lstinline!x! and/or \lstinline!y!.
+When \lstinline!legend! is not provided, the tool produces a default based on \lstinline!x! and/or \lstinline!y!.
 Providing the empty string as \lstinline!legend! means that the curve shall be omitted from the plot legend.
 Variable replacements, as described in \cref{variable-replacements}, can be used in \lstinline!legend!.
 

chapters/functions.tex

@@ -1573,7 +1573,7 @@ \section{Declaring Inverses of Functions}\label{declaring-inverses-of-functions}
 Hence, providing an inverse function cannot be used as a means to select a particular solution to a nonlinear equation with multiple solutions (in other words, to select particular pre-image for a non-injective function).
 On the contrary, providing an inverse function can make a model ambiguous, as it won't be known if an equation is solved using a generic nonlinear equation solver (with solution being influenced by guess values), or solved using the provided inverse (possibly selecting a different solution).
 
-While it is possible to have several inverse functions that could be applied to solve the same equation, the real problem of ambiguity isn't the number of applicable inverse functions, but that there is ambiguity as soon as there is one inverse function and multiple solutions.
+While it is possible to have several inverse functions that could be applied to solve the same equation, the real problem of ambiguity is not the number of applicable inverse functions, but that there is ambiguity as soon as there is one inverse function and multiple solutions.
 Since ambiguity is inherent when inverse functions are provided, a tool shall not give any diagnostic regarding ambiguity due to use of inverse functions, even when making a choice between several applicable ones.
 \end{nonnormative}